Key period of abstinence limiting superior food (8)
I believe the answer is:
esculent
'food' is the definition.
(formal term for something edible)
'key period of abstinence limiting superior' is the wordplay.
'key' becomes 'esc' ('Escape' key on a computer keyboard).
'period of abstinence' becomes 'lent' (I've seen this before).
'limiting' is an insertion indicator.
'superior' becomes 'u' (I've seen this in other clues).
'esc'+'lent'='esclent'
'esclent' placed around 'u' is 'ESCULENT'.
(Other definitions for esculent that I've seen before include "ready to be put away" , "Palatable" , "worth digesting" .)