Crossword Genius

One withdraws before the wine is served (6,6)

Ross

I believe the answer is:

bottle opener

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'one' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for bottle opener that I've seen before include "one could get cap knocked off!" , "Kitchen utensil" , "Device removing drink caps" , "Prising implement" , "Cap remover" .)

I've seen this clue in The Globe and Mail.
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