scare up

先日 "scare the crap out of me" を採り上げましたが、その "scare" とは全く関係なさそうな "scare" が小説 Ringに出てきました。
In a lane in front of Kinomiya Station was a small one-story house with a shingle by the door that read Nagao Clinic: Internal Medicine and Pediatrics. Asakawa and Ryuji stood in front of the door for some time. If they couldn't pull any information out of Nagao, it'd be sorry, time's up! There was no more time to scare up new leads.
"scare up" が慣用句の様な気がします。とにかく辞書で調べます。
・Merriam-Webster's Online Dictionary: to find or get together with considerable labor or difficulty: scrape up: managed to scare up the money: I can probably scare up my old textbooks if you need them.
・Wiktionary: (figuratively) To find or procure, especially something not easily found or procured: With the current budget crunch and the Fingertip case inactive, I couldn’t scare up much enthusiasm.
・McGraw-Hill Dictionary of American Idioms and Phrasal Verbs: to search for and find someone or something. Go out in the kitchen and scare some food up. I'll see if I can scare up somebody to fix the broken chair.
やはり "scare up" は慣用句でしたね。でも "scare up" がどうしてこの様な意味になるのか不思議です。