WHOLE CHARACTER
吹chuī
to blow (吹灯, 风吹); to brag (吹牛, 吹嘘); to fail; to fall through (吹台); to spread (鼓吹)
吹 is to blow — the wind, your own horn, or a plan gone bust.
The header says 左形右声 without naming the right piece; the mouth radical is clear, and 欠's sound link is historical.
MEANING (THE MOUTH RADICAL)
口kǒu
mouth; opening
Mouth/speech/opening clue; may also be a repeated visual element.
In 吹: meaning (the mouth radical) Shown with its documented or clearly limited role.
SOUND
欠qiàn
to owe; to lack
Standalone meaning is kept separate from its role in other characters.
In 吹: sound The right piece; chuī shares none of 欠's modern syllable exactly — the link is historical.