Tinned food fish (4)
I believe the answer is:
tuna
'tinned food fish' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for tuna that I've seen before include "Type of fish" , "Sea creature" , "Large fish for the strange aunt" , "Large tasty fish, fond of a nut" , "Skipjack --, blue-fin --" .)