With the addition of some plump, luscious fruit (4)
I believe the answer is:
plus
'with the addition of' is the definition.
(I've seen this before)
'some plump luscious fruit' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'PLUS' is hidden in the letters of 'plump luscious fruit'.
(Other definitions for plus that I've seen before include "Added extra" , "Together with; advantage" , "Coupled with" , "And, arithmetically" , "An advantage; positive" .)