Tinned food fish (4)
I believe the answer is:
tuna
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tinned food fish</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(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 --" .)