Legalised foodstuff that's held back (6)
I believe the answer is:
silage
'legalised foodstuff that's held back' is the definition.
I can't tell whether this defines the answer.
'legalised foodstuff that's held back' is the wordplay.
'that's held' indicates a hidden word.
'back' says the letters should be written in reverse.
'egalis' can be found hidden inside 'legalised foodstuff'.
'egalis' reversed gives 'SILAGE'.
(Other definitions for silage that I've seen before include "Fodder in store" , "Animal feed" , "Crop harvested for fodder" , "Animal food" , "Preserved fodder for cattle" .)