Foreign language - could be French (6)
I believe the answer is:
polish
'foreign language' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for polish that I've seen before include "'Buff, burnish (6)'" , "Buff - from Poland" , "Shine up the nationality" , "European language - refinement" , "Shine up in Warsaw" .)