Go mad when retired (4)
I believe the answer is:
stab
'go' is the definition.
(both can mean an attempt)
'mad when retired' is the wordplay.
'mad' becomes 'bats' (informal term for mad).
'when retired' says the letters should be written in reverse.
'bats' backwards is 'STAB'.
(Other definitions for stab that I've seen before include "Strike with knife" , "Thrust (weapon into)" , "effort" , "wound as Casca" , "Inflict wound with knife" .)