Make fruit cake (5)
I believe the answer is:
donut
'cake' is the definition.
(donut is a kind of cake)
'make fruit' is the wordplay.
'make' becomes 'do' (doing is a kind of making).
'fruit' becomes 'nut' (nut is a kind of fruit).
'do'+'nut'='DONUT'
(Other definitions for donut that I've seen before include "cake in the American way" , "Sugary deep-fried cake" , "something to eat" , "ring coming across the Atlantic" , "cake, American-style" .)