Fights about casserole containing fine seafood (9)
I believe the answer is:
swordfish
'seafood' is the definition.
(swordfish is a kind of seafood)
'fights about casserole containing fine' is the wordplay.
'fights' becomes 'rows' (I've seen this in another clue).
'about' is a reversal indicator.
'casserole' becomes 'dish' (casserole is a kind of dish).
'containing' indicates putting letters inside.
'fine' becomes 'f' (abbreviation).
'rows' backwards is 'swor'.
'dish' enclosing 'f' is 'dfish'.
'swor'+'dfish'='SWORDFISH'
(Other definitions for swordfish that I've seen before include "seafood" , "Marine creature with very long upper jaw" , "Creature using its long jaw to stab" , "(Edible) long-snouted swimmer" , "Large marine creature" .)