One first-class (3)

I believe the answer is:

ace

I believe this clue is a double definition.

'one' is the first definition.
(ace has a value of one in some card games)

'first-class' is the second definition.
(synonyms)

(Other definitions for ace that I've seen before include "Unreturnable serve" , "Adept" , "Playing card with single spot" , "even higher than the king" , "Crack" .)

I've seen this clue in the Evening Standard.

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