To Stray
To Turn Away, To Digress, To Deviate
intransitive verb, ichidan verb
You already learned that 逸らす means "to turn away," so this means that but also to stray.
それる
はぐれる
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You've already learned this mnemonic but here's a quick review:
If you're the type of person who starts to stray easily, you'll end up saying sorry (それ) a lot. Even if you don't do it often, if you stray, say sorry!
すぐ話が脇道へ逸れてしまう。
The conversation quickly digressed.