Go out to lunch when retired (4)
I believe the answer is:
stab
'go' is the definition.
(both can mean an attempt)
'out to lunch when retired' is the wordplay.
'out to lunch' becomes 'bats' (both can mean mad).
'when retired' is a reversal indicator.
'bats' in reverse letter order is 'STAB'.
(Other definitions for stab that I've seen before include "Puncture" , "Strike with knife" , "Pierce with a knife" , "Thrust (weapon into)" , "Twinge; guess" .)