'clip-on' definitions:

Definition of 'clip-on'

(from WordNet)
adjective
Attachable by a clip; "clip-on earrings"; "a clip-on bow tie"
noun
A device (as an earring, sunglasses, microphone etc.) that is attached by clips

Definition of 'clip-on'

From: GCIDE
  • clip-on \clip-on\ adj. having a clip as the means of attachment; as, clip-on earrings; a clip-on bow tie. [WordNet 1.5]