clockwork crocodile

Chocolate Factoryでは、Mr. Wonkaがジャングルから連れてきた小人のOompa-Loompasが働いています。こOompa-Loompasが話のところどころで歌をうたいます。　チューインガム中毒の少女がChocolate Factoryで食べてはいけないと言われたチューインガムを手にして食べ、トラブルになった時にもOompa-Loompasが歌います。
For half an hour she lay and read,
Chewing and chewing all the while
Like some great clockwork crocodile.
この "clockwork crocodile" の表現がよく分からないので、 "clockwork" 辞書で引きます。
・Collins Dictionary: 1.the mechanism of a clock 2.any similar mechanism, as in a wind-up toy: "This is a well-oiled machine and it goes like clockwork ," he says.: with complete regularity and precision: She rose at six, took a nap in the afternoon and went to bed at 9.30 like clockwork.
・Macmillan Dictionary: [only before noun] operated by a set of springs that work when you turn a handle or key
・Vocabulary.com: any mechanism of geared wheels that is driven by a coiled spring; resembles the works of a mechanical clock: In addition to clockwork toy monsters, there are also some horrific sketches of people who had utilized Elizabeth’s “tears.”
あごの強いワニが機械仕掛けのワニのようにガムをかんでいるイメージのようです。