Economise with hot instead of cold seafood (6)
I believe the answer is:
shrimp
'seafood' is the definition.
(shrimp is a kind of seafood)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for shrimp that I've seen before include "Raising of a siege" , "tiny chap" , "Small prawn-like creature" , "Diminutive person" , "Small edible shellfish, pink when boiled" .)