Not occupied? There's no hurry (2,7)

I believe the answer is:

at leisure

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'not' is the definition.
Both the answer and definition are adverbs. Maybe you can see an association between them that I don't see?

I don't understand the rest of the clue.

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(Other definitions for at leisure that I've seen before include "in an unhurried fashion" , "resting" , "See ritual while taking it easy" , "Relaxing, not working" , "free" .)

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

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