Polish some rubies (3)

I believe the answer is:

rub

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'polish' is the definition.
(polish meaning rub to make shiny)

I can't explain the rest of the clue.

(Other definitions for rub that I've seen before include "Cause friction" , "Ointment for skin" , "Polish - difficulty" , "Irritate-...the wrong way" , "Massage or buff" .)

I've seen this clue in the Evening Standard.

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