Unlikely to be patient much longer? (12)

I believe the answer is:

convalescent

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

I don't understand the rest of the clue.

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(Other definitions for convalescent that I've seen before include "One who's recovering" , "One may be showing improvement" , "getting back to normal" , "Novel accents (anag) -- gradually recovering health" , "Person picking up" .)

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

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