Right
欠 is the yawn radical, the indexing component — a person with mouth open, leaning forward, breath issuing out. It anchors
欲 in the family of mouth-and-breath words tied to longing or sound:
歌 to sing,
饮 to drink,
歇 to rest,
欢 joyful. The image is desire as an open-mouthed reaching toward what is missing.
