Buff, rub (6)
I believe the answer is:
polish
This clue is a double definition.
'buff' is the first definition.
(I know that buff can be written as polish)
'rub' is the second definition.
(I've seen this before)
(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" .)