Fold in a petal, possibly (5)
I believe the answer is:
pleat
'fold' is the definition.
(I know that pleat is a type of fold)
'a petal possibly' is the wordplay.
'possibly' indicates anagramming the letters.
'petal' with letters rearranged gives 'PLEAT'.
'in' acts as a link.
(Other definitions for pleat that I've seen before include "Double fold in a garment" , "Fold formed in fabric" , "Gather" , "Leapt (anag)" , "Crease" .)