Card expert (3)

I believe the answer is:

ace

I believe this clue is a double definition.

'card' is the first definition.
(ace is a type of playing card)

'expert' is the second definition.
(ace can informally mean very good)

(Other definitions for ace that I've seen before include "In golf, a hole in one" , "'wicked'!" , "Possibly a diamond" , "reason for point of no return" , "Crack" .)

I've seen this clue in the Evening Standard.

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