Loaf brought back with a fish (4)
I believe the answer is:
tuna
'fish' is the definition.
(tuna is a type of fish)
'loaf brought back with a' is the wordplay.
'loaf' becomes 'nut' (I've seen this in other clues).
'brought back' is a reversal indicator.
'with' means one lot of letters go next to another.
'nut' back-to-front is 'tun'.
'tun'+'a'='TUNA'
(Other definitions for tuna that I've seen before include "Large sea-fish" , "Popular food fish" , "swimmer" , "Large edible sea fish, often canned" , "Large salt water fish" .)