Gather into wrinkles (6)
I believe the answer is:
pucker
'gather into wrinkles' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for pucker that I've seen before include "Gather into wrinkles, cause lips to bulge" , "Gather into bulge, say lips" , "Form into wrinkles" , "Gather skin into folds" , "Purse lips, or gather into wrinkles" .)