Is about to eat affected seafood (6)
I believe the answer is:
scampi
'seafood' is the definition.
(type of seafood)
'is about to eat affected' is the wordplay.
'about' is an anagram indicator.
'to eat' indicates putting letters inside.
'affected' becomes 'camp' (camp can mean exaggerated or affected).
'is' with letters rearranged gives 'si'.
'si' placed around 'camp' is 'SCAMPI'.
(Other definitions for scampi that I've seen before include "Fried seafood" , "Cooked Norway lobsters" , "Dish of fried shrimps or prawns" , "Fish dish, often in rings" , "Breaded prawns" .)