Not entirely round fruit (4)
I believe the answer is:
plum
'fruit' is the definition.
(I know that plum is a type of drupe)
'not entirely round' is the wordplay.
'not entirely' means to remove the last letter (not all of the word).
'round' becomes 'plump' (both can mean fat or chubby).
'plump' with its last letter taken away is 'PLUM'.
(Other definitions for plum that I've seen before include "Lump of fruit" , "superior kind?" , "Dark bluish-red - fruit" , "excellent?" , "murderer" .)