So good nobody will play you? (9)

I believe the answer is:

matchless

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'so' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for matchless that I've seen before include "Unbeatable" , "reason for rubbing sticks together?" , "Having no equal" , "Like the top" , "Unrivalled" .)

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

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