Beat unconscious, then execute! (5)
I believe the answer is:
outdo
'beat' is the definition.
(outdoing is a kind of beating)
'unconscious then execute' is the wordplay.
'unconscious' becomes 'out' ('out' can be similar in meaning to 'unconscious').
'then' says to put letters next to each other.
'execute' becomes 'do' (doing is a kind of executing).
'out'+'do'='OUTDO'
(Other definitions for outdo that I've seen before include "Surpass someone at something" , "Beat" , "Perform better than (someone)" , "Perform better than surpass" , "Surpass, go one better than" .)