A timing technique - an interruption of gait rather than a kick - drawn from the karate concept of go no sen (response after the initiation).
Collapse forward pressure with a subtle knee redirection they can't see coming.
The knee clip lives in the half-beat between your opponent's steps. As their lead foot lifts, your rear knee travels forward and inward, meeting the inside of their supporting knee.
Drive through the target rather than into it. Their step collapses, their weight buckles inward, and their upper body pitches forward.
The clip is a setup, not a finish. Chain immediately to a palm heel or elbow while their posture is broken, then return your kicking leg to a covered stance.