Scold a blundering beater! (6)
I believe the answer is:
berate
'scold' is the definition.
(I know that scold can be written as berate)
'a blundering beater' is the wordplay.
'a blundering' is an anagram indicator (I've seen 'blunders' mean this).
'beater' anagrammed gives 'BERATE'.
(Other definitions for berate that I've seen before include "Reprimand" , "Angrily scold/criticise" , "Carpet" , "Condemn" , "Scold; angrily criticise" .)