Seafood in ship raw necessarily (5)
I believe the answer is:
prawn
'seafood' is the definition.
(I know that prawn is a type of seafood)
'in ship raw necessarily' is the wordplay.
'in' indicates the answer is hidden within the clue.
'PRAWN' can be found hidden inside 'ship raw necessarily'.
(Other definitions for prawn that I've seen before include "Large shrimp" , "Small, edible crustacean" , "Small tasty crustacean, nice in cocktail" , "Cocktail ingredient" , "Bit of seafood" .)