Not doing anything - just sitting empty (10)

I believe the answer is:

unoccupied

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'empty' is the definition.
(similar in meaning)

'not doing anything just sitting' is the wordplay.
I cannot really see how this works, but
'not' could be 'no' (negative) and 'no' is located in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

(Other definitions for unoccupied that I've seen before include "Empty" , "Not tenanted" , "idle" .)

I've seen this clue in the Evening Standard.

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