Form heaps perhaps (5)
I believe the answer is:
shape
'form' is the definition.
(synonyms)
'heaps perhaps' is the wordplay.
'perhaps' indicates an anagram.
'heaps' with letters rearranged gives 'SHAPE'.
(Other definitions for shape that I've seen before include "External form" , "Phase (anag.)" , "Form, figure" , "For good physical condition" , "'Figure, outline (5)'" .)