Crossword Genius

Number working, twelve (4)

Ross

I believe the answer is:

noon

'twelve' is the definition.
(twelve noon)

'number working' is the wordplay.
'number' becomes 'no' (abbreviation).
'working' becomes 'on' (on can mean working or activated).
'no'+'on'='NOON'

(Other definitions for noon that I've seen before include "12 o'clock" , "High time of day?" , "The middle of the day" , "Twelve o'clock in the day" , "when only mad dogs go out?" .)

I've seen this clue in The Telegraph.
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