Seafood garnish (5)
I believe the answer is:
aspic
'seafood garnish' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for aspic that I've seen before include "Savoury jelly for coating meat, eggs etc" , "Ending of Marlowe's thriller" , "Savoury relish" , "Jelly based on fish or meat stock" , "garnish" .)