Defeat right away (4)
I believe the answer is:
rout
'defeat' is the definition.
(I know that rout is a type of defeat)
'right away' is the wordplay.
'right' becomes 'r' (common abbreviation).
'away' becomes 'out' (synonyms).
'r'+'out'='ROUT'
(Other definitions for rout that I've seen before include "Put to flight on tour" , "Inflict heavy defeat on" , "Easy victory (or defeat)" , "Disastrous defeat" , "Completely defeat" .)