Napoleon's characteristic card game? (4)

I believe the answer is:

solo

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'card game?' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for solo that I've seen before include "Type of whist" , "Done by one person" , "On one's own, unaccompanied" , "Han - (Star Wars); fly unaccompanied" , "Unaccompanied passage" .)

I've seen this clue in the Evening Standard.

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