Still a number going topless (4)

I believe the answer is:

even

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'still' is the definition.
('even' can be a synonym of 'still')

'a number going topless' is the wordplay.
'a number' becomes 'eve' (I can't explain this - if you can you should give a lot more credence to this answer).
'going' becomes 'on' (both can mean functioning or activated).
'topless' means to remove the first letter.
'on' with its first letter taken off is 'n'.
'eve'+'n'='EVEN'

Can you help me to learn more?

(Other definitions for even that I've seen before include "Describes a number divisible by two" , "Regular - smooth" , "Flattened" , "Regularly; yet" , "Yet; level" .)

I've seen this clue in The Times.

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