Update at noon? (5)

I believe the answer is:

amend

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'update' is the definition.
(I've seen this in another clue)

I cannot understand how the rest of the clue works.

(Other definitions for amend that I've seen before include "Rectify" , "Corrct error, make a minor aleration" , "Change for the better" , "make an improvement" , "Change to improve" .)

I've seen this clue in The Telegraph.

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