Legal officials working overtime on sign (8)

I believe the answer is:

notaries

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

'working overtime on sign' is the wordplay.
'working overtime on' becomes 'not' (I am not sure about this - if you are sure you should believe this answer much more).
'sign' becomes 'Aries' (star sign).
'not'+'aries'='NOTARIES'

Can you help me to learn more?

(Other definitions for notaries that I've seen before include "Legal clerks" , "legal professionals?" , "Offices who draw up and witness documents" , "They witness official documents" , "Public officials" .)

I've seen this clue in The Guardian.

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