Confute (5)
I believe the answer is:
rebut
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">confute</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know this)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for rebut that I've seen before include "Refute - disprove" , "Quash" , "Prove the claim wrong" , "Rebuff; deny" , "Scotch" .)