This is the formal, literary reading of 嚼. In modern Chinese it is almost always bound inside 咀嚼 (to masticate; figuratively to ponder over). For ordinary chewing in speech, use the jiáo reading instead.
Mouth radical on the left, the indexing radical, marking 嚼 as a mouth action. To 嚼 is to chew, the prototypical thing the mouth does to food. Family: 吃 (eat), 喝 (drink), 咬 (bite), 吞 (swallow). Doing semantic work, not just classifying.
Right 爵 supplies the sound. The reading jué drifted to jiáo in everyday speech, while the original jué survives in the literary 咀嚼. 爵 itself depicts a three-legged ritual wine vessel; the link to chewing is purely phonetic. 嚼 has no other common 爵 siblings, so it stands alone.
