Root around this counter (5)
I believe the answer is:
rebut
'this counter' is the definition.
(thesaurus)
'root around' is the wordplay.
'root' becomes 'tuber' (I've seen this before).
'around' is a reversal indicator.
'tuber' written backwards gives 'REBUT'.
(Other definitions for rebut that I've seen before include "Refute - disprove" , "Tuber (anag.)" , "Brute (anag)" , "Quash" , "Claim or prove to be false" .)