Wrinkle or fold (7)
I believe the answer is:
crinkle
This clue is a double definition.
'wrinkle' is the first definition.
(synonyms)
'fold' is the second definition.
(crinkling is a kind of folding)
(Other definitions for crinkle that I've seen before include "Small crease or wrinkle" , "Clinker (anag.)" , "Curl" .)