credit to

アンはQueen's の入学試験にトップの成績で合格します。
I just guess she has done well, and far be it from me to be backward in saying it. You're a credit to your friends, Anne, that's what, and we're all proud of you.
この "credit" は私の知っている "credit" の意味ではないようなので辞書を見ます。
名詞の意味だけでもDictionary.comには１３項目ありました。　引用文と同じ様な意味・用法は次ぎの説明だと思います。
Dictionary.com: a source of pride or honor: You are a credit to your school.
American Herritage Dictionary: A source of honor or distinction: This exceptional athlete is a credit to our team.
アンは友達にとっても誇り、自慢だと言う事でしょうか。

iridescent colours

リーダーズダイジェスト9月号のMy Storyにあった文です。
Tiny fish darted through the water flashing iridescent colours - pink, green, mauve, blue and silver.
"iridescent colours" は何色でしょうか？　後に色々な色が続いているので特定の色では無いようですが。　辞書を見ます。
OneLook Quick Definitions:　1) having a play of lustrous rainbow-like colors ("An iridescent oil slick") 2) varying in color when seen in different lights or from different angles ("A dragonfly hovered, vibrating and iridescent")
Dictionary.com: displaying a play of lustrous colors like those of the rainbow.
語源辞典 Online Etymologyを見ると：　1796, coined from L. iris (gen. iridis) "rainbow" (see iris).
"iridescent colours" は日本語の虹色、玉虫色に相当するようです。

gird up their loins for the fray

赤毛のアンも後半になりました。
Especially did the Queen's class gird up their loins for the fray, for at the end of the coming year, dimly shadowing their pathway already, loomed up that fateful thing known as "the Entrance," at the thought of which one and all felt their hearts sink into their very shoes.
"gird up their loins for the fray" の個所のそれぞれの単語は少なくとも一部の意味を
知っている単語ですが全体では意味がよく分かりません。 辞書を見ると　"gird up their loins" は慣用句としての意味がある事が分かりました。
Wiktionary: To prepare oneself for something demanding. Literally referred to the need to strap a belt around one's waist when getting up in order to avoid the cloak falling off.
Dictionary.com: gird or gird up one's loins, to prepare oneself for something requiring readiness, strength, or endurance: He girded his loins to face his competitor.
では "for the fray" の "fray" の意味は何でしょうか？
Dictionary.comの名詞としての意味欄には次ぎの項目があります。
1. a fight, battle, or skirmish.
2. a competition or contest, esp. in sports.
3. a noisy quarrel or brawl.
引用文での "fray" は学業での競争の意味でしょう。　それにしてもアンを含め 赤毛のアンに出てくる学生は勉強意欲に燃えていて感心します。

shirk

数日前にＴＶでＢＢＣ製作のジンベイザメ（whale shark）の生態についてのドキュメンタリーを見ましたが、赤毛のアンにもシャークが出てきます。　
Rachel is a good Christian woman and she means well. There isn't a kinder soul in Avonlea and she never shirks her share of work.
この動詞の "shirks" ですが、私の知っている名詞のシャークとはよく見るとスペルも違います。（発音も一寸違いますね）　しかたがないので辞書を引きます。
OneLook Quick Definitions: avoid dealing with ("She shirks her duties"); avoid (one's assigned duties) ("The derelict soldier shirked his duties")
Dictionary.com: 1(used with object). to evade (work, duty, responsibility, etc.). 2(used without object). to evade work, duty, etc.
辞書の例文にある "derelict" も "shirk" と意味に関係がある様なので覚えておきたい。
"derelict" も辞書を見ます。
OneLook Quick Definitions:　noun: 1.　a person unable to support himself; 2. a ship abandoned on the high seas; adjective: 1. failing in what duty requires ("Derelict (or delinquent) in his duty") 2. deserted or abandoned as by an owner ("A derelict ship")
Dictionary.com:
・adjective 1. left or deserted, as by the owner or guardian; abandoned: a derelict ship.
2. neglectful of duty; delinquent; negligent.
・noun 3. a person abandoned by society, esp. a person without a permanent home and means of support; vagrant; bum.
4. Nautical. a vessel abandoned in open water by its crew without any hope or intention of returning.
5. personal property abandoned or thrown away by the owner.
6. one guilty of neglect of duty.
7. Law. land left dry by a change of the water line.
やはり、やるべき事は怠らずに責任を果たす、当然と言えば当然なので "I never shirk my share of work." を肝に銘じましょう 。

might and main

夏休みが終わってアンは勉強を再開するのにやる気満々です。
"I feel just like studying with might and main," she declared as she brought her books down from the attic.
"might and main" は初めて見る表現ですが、文脈からして全力でと言うような意味と推測できます。　辞書で確認します。
・Cambridge Idioms Dictionary: with all your effort and strength War is something we should be working might and main to avoid.
・McGraw-Hill Dictionary of American Idioms and Phrasal Verbs: Cliche great physical strength; great force. The huge warrior, with all his might and main, could not break his way through the castle gates. The incredible might and main of the sea crushed the ship against the cliff.
Dictionary.com: with all the vigor, force, or energy at one's command: They pulled with might and main.
"with all one's might" は見たことがありますが、似た表現に "with all one's might and main" もあるそうです。
私も "I will study English with all my might and main." と言えれば良いのですが、当面は英語より卓球、テニス、ランニングなどの体力増強の方にやる気満々なので、英語は頭の軽い体操程度で楽しみたい。

halal food

The Japan Times Online、Oct.10 の記事タイトルからです。
Kyoto University to serve halal food
"halal food" は食べたことはありませんが記事を読むと意味は分かります。
Kyoto University will start providing food permissible under Islamic law at the school's cafeteria to meet the needs of the increasing number of Muslim students on campus.
（中略）
The cafeteria will introduce a halal food corner from Tuesday, avoiding pork and seasonings of pork origin, which Muslims are banned from eating. The new menus include chicken and croquettes made of broad beans, it said.
と言う事で、豚肉を避けたイスラム教徒用の食事が "halal food" なのですね。　一応 "halal" の辞書の説明も見ます。
OneLook Quick Definitions: (Islam) meat from animals that have been slaughtered in the prescribed way according to the shariah; adjective: proper or legitimate ("The fund earns halal profits in full compliance with the Shari'a"); conforming to dietary laws ("Halal meat")
Dictionary.com: n. Meat that has been slaughtered in the manner prescribed by the shari'a.; adj. Of or being meat slaughtered in the prescribed way: a halal butcher; a halal label., In accordance with or permitted under the shari'a.
豚肉さえ使っていなければ良いと言う訳ではなさそうですが、カツ丼が好きな私としては "halal food" を食べたいとは思わないのでこれ以上の深追いは止めます。

fastest runner

午前中江戸川マラソン（正確には10kmランです）に参加してきました。　いつもの自分のペースで走ったので記録も例年通りの５５分台でした。　そんな訳で今日はレースにちなんだジョークです。　
"Who was the fastest runner in history?"
"Adam. He was the first in the human race."

get into scrapes

アンがMarillaにMrs. Allanが言った事を話している会話の一部です。
She told me so herself--that is, she said she was a dreadful mischief when she was a girl and was always getting into scrapes.
"getting into scrapes" は慣用句かと思いましたが慣用句としては辞書にありません。　そこで私の知っている "scrape" 以外の意味を調べます。
Dictionary.com: a) an embarrassing or distressing situation; predicament: He is always in some kind of a scrape. b) a difference of opinion, fight, or quarrel; scrap.
Cambridge Advanced Learner's English Dictionary: informal a difficult or slightly dangerous situation which you cause by your own silly behaviour; She's always getting into silly scrapes - I do wish she'd think before she does things.; He had a couple of scrapes with the police and ended up in court.
なるほど、"getting into scrapes" はいたずらや喧嘩などをして困った事になるのですね。
"get into scrapes" の表現はアンが髪の毛を緑に染めた事件を起した時にMarillaも次のように使っていました。
"Come right down to the kitchen--it's too cold up here--and tell me just what you've done. I've been expecting something queer for some time. You haven't got into any scrape for over two months, and I was sure another one was due. Now, then, what did you do to your hair?"
Marillaの言い方は実に皮肉がこもっていますね。

bring down the house

子供達のコンサートが開かれお喋りが得意なアンは朗読をしました。
"Well, your recitations just brought down the house, Anne. That sad one was simply splendid."
"brought down the house" は明らかに慣用句の様です。
Dictionary.com: to call forth vigorous applause from an audience; be highly successful: The children's performances brought down the house.
Merriam-Webster's Online Dictionary: (or bring the house down): to win the enthusiastic approval of the audience
現在ならスタンディングオベーションになるところだったのでしょうか。

mole

The Japan Times Online、Oct. 5のタイトルに興味を引く表現がありました。
Postwar defense aide was CIA mole
"mole" と言うとモグラを連想します。　日本語で言う警察の犬（警察犬ではなく警察の手先の意味で）と似ている気がしますがどうでしょうか？　記事を読んでみます。
An aide to Prime Minister Shigeru Yoshida gave internal government information to the U.S. Central Intelligence Agency in the 1950s on Japan's moves to develop a defense capability.
（中略）
Tatsumi was a member of the so-called Kawabe Organization, an anticommunist spy ring established at the request of the General Headquarters of the U.S.-led Occupation, where he was involved in the planning stages of establishing new military and intelligence organizations.
手先も手先、スパイの意味があるようです。　辞書で "mole" を引いてみます。
OneLook Quick Definitions: a spy who works against enemy espionage
Dictionary.com: a spy who becomes part of and works from within the ranks of an enemy governmental staff or intelligence agency.
確かに "mole" の方が犬よりも敵の内部深くに侵入できそうですね。