Relative's grubby leaving sauna on a regular basis (5)

I believe the answer is:

uncle

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'relative's' is the definition.
(uncle is a kind of relative)

I don't understand the rest of the clue.

(Other definitions for uncle that I've seen before include ". . . . . Sam, the US government" , "Pawnbroker's nickname" , "Law enforcement body" , "Brother of one's parent" , "Family relation" .)

I've seen this clue in The Telegraph.

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