Custard apple makes desserts work (8)
I believe the answer is:
sweetsop
'custard apple' is the definition.
(sweetsop is a kind of custard apple)
'desserts work' is the wordplay.
'desserts' becomes 'sweets' ('sweet' can be a synonym of 'dessert').
'work' becomes 'op' (short for opus).
'sweets'+'op'='SWEETSOP'
'makes' acts as a link.
(Other definitions for sweetsop that I've seen before include "Custard apple" , "West Indian fruit" , "American shrub" , "Tropical shrub" , "fruit tree" .)