Fiery deity served up food (3,3)
I believe the answer is:
hot dog
'food' is the definition.
(I've seen this before)
'fiery deity served up' is the wordplay.
'fiery' becomes 'hot' (synonyms).
'deity' becomes 'god' (a deity is a god or divine being).
'served up' shows that the letters should be reversed in order.
'god' written backwards gives 'dog'.
'hot'+'dog'='HOT DOG'
(Other definitions for hot dog that I've seen before include "Sausage in a bun" , "food from a stand?" , "'Frankfurter in a bun (3,3)'" , "Sausage in a bap" , "Sausage in bread-roll for thermal canine" .)