The suaveness of those Slavs (6)

I believe the answer is:

polish

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'the suaveness' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Maybe they are linked in a way I don't understand?

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for polish that I've seen before include "tongue" , "Brush up" , "Perfect" , "Beeswax, for example" , "class" .)

I've seen this clue in the Evening Standard.

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