Berate about reduction (6)
I believe the answer is:
rebate
'reduction' is the definition.
(thesaurus)
'berate about' is the wordplay.
'about' indicates an anagram.
'berate' anagrammed gives 'REBATE'.
(Other definitions for rebate that I've seen before include "Refund - discount" , "Reduction in the cost" , "Give back (money)" , "Money back, partial refund" , "A bit taken off wood" .)