Twelve numbers, back to back (4)

I believe the answer is:

noon

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'twelve' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for noon that I've seen before include "See 8" , "The middle of the day" , "12 o'clock" , "[LUNCHTIME] ?" , "when PM starts" .)

I've seen this clue in The Times.

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