Plan return of huge pastries (9)
I believe the answer is:
stratagem
'plan' is the definition.
(stratagem is a kind of plan)
'return of huge pastries' is the wordplay.
'return of' says the letters should be written in reverse.
'huge' becomes 'mega' (mega can mean very large).
'pastries' becomes 'tarts' (tart is a kind of pastry).
'mega'+'tarts'='megatarts'
'megatarts' in reverse letter order is 'STRATAGEM'.
(Other definitions for stratagem that I've seen before include "Device" , "way to outwit opponent" , "could be a trick" , "Manoeuvre - Ma's target (anag)" , "A cunning plan or piece of trickery" .)