Killed and cooked snail (5)
I believe the answer is:
slain
'killed' is the definition.
(slaying is a kind of killing)
'cooked snail' is the wordplay.
'cooked' indicates anagramming the letters (letters cooked into a new form).
'snail' anagrammed gives 'SLAIN'.
'and' acts as a link.
(Other definitions for slain that I've seen before include "Violently killed" , "Slaughtered" , "Put to the sword" , "Killed, murdered" .)