Seafood bishop fed to confused monarch (7)
I believe the answer is:
lobster
'seafood' is the definition.
(lobster is a kind of seafood)
'bishop fed to confused monarch' is the wordplay.
'bishop' becomes 'b' (abbreviation used in chess).
'fed to' is an insertion indicator.
'confused' becomes 'lost' ('lost' can be a synonym of 'confused').
'monarch' becomes 'er' (abbreviation for Elizabeth Regina).
'b' placed inside 'lost' is 'lobst'.
'lobst'+'er'='LOBSTER'
(Other definitions for lobster that I've seen before include "Tommy no longer" , "Edible marine crustacean" , "It turns bright-red when cooked" , "food?" , "Bolster up te shellfish" .)