扰

Left-side hand radical, the three-stroke side form of 手. Indexes 扰 in the hand-action family alongside 拉 to pull, 推 to push, 打 to hit. To disturb is to put a hand where it isn't wanted: the radical names the meddling fingers stirring up trouble.

Right side 尤 supplies the sound: yóu drifted to rǎo via a regular y/r alternation with vowel and tone change. The simplified 扰 replaces the traditional 擾 phonetic 憂 with the much shorter 尤, picked purely as a sound proxy. The fault, blame nuance of 尤 happens to suit a verb meaning to bother.