Crossword Genius

Checker, perhaps, who won't be sticking at twenty-one (7)

Ross

I believe the answer is:

twister

This clue is a double definition.

'checker perhaps' is the first definition.
(Chubby Checker recorded the song The Twist)

'who won't be sticking at twenty-one' is the second definition.
(as in sticking or twisting in the card game 21)

(Other definitions for twister that I've seen before include "Tornado (colloq.)" , "Funnel-shaped wind" , "Crook - tornado" , "One dancing" , "A swindler or a cyclone" .)

I've seen this clue in The Guardian.
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