Beat counter drunkenly (7)
I believe the answer is:
trounce
'beat' is the definition.
(I know that beat can be written as trounce)
'counter drunkenly' is the wordplay.
'drunkenly' indicates an anagram.
'counter' with letters rearranged gives 'TROUNCE'.
(Other definitions for trounce that I've seen before include "Clobber" , "Massacre" , "Beat roundly" , "Thump" , "Defeat decisively" .)