Sort of ball needed for games? (6)

I believe the answer is:

rubber

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'sort of ball' is the definition.
(rubber ball)

I can't explain the remainder of the clue.

(Other definitions for rubber that I've seen before include "Something you get in bridge" , "Elastic substance from trees" , "a bit of bridge" , "item in 27 [BRIDGE]?" , "One polishing" .)

I've seen this clue in the Evening Standard.

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