Buff, rub (6)
I believe the answer is:
polish
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">buff</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that buff can be written as polish)</span><br/ ><br/ >'<span class="explanation-format__original">rub</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for polish that I've seen before include "Make smooth and glossy" , "A West Slavic language" , "Buff - from Poland" , "Shine up in Warsaw" , "Give shine to" .)