Seafood, cold, local sent back (4)
I believe the answer is:
crab
'seafood' is the definition.
(crab is a kind of seafood)
'cold local sent back' is the wordplay.
'cold' becomes 'c' (eg on taps).
'local' becomes 'bar' (I've seen this before).
'sent back' shows that the letters should be reversed in order.
'bar' back-to-front is 'rab'.
'c'+'rab'='CRAB'
(Other definitions for crab that I've seen before include "Marine crustacean (seen on 1 across?)" , "One may be caught" , "one is a fiddler" , "Nautical nipper" , "Scuttling crustacean" .)