Dead snail, maybe (5)
I believe the answer is:
slain
'dead' is the definition.
(similar in meaning)
'snail maybe' is the wordplay.
'maybe' indicates anagramming the letters.
'snail' anagrammed gives 'SLAIN'.
(Other definitions for slain that I've seen before include "Violently killed" , "Put to the sword" , "Slaughtered" , "Killed, murdered" .)