Public official never admits to being promoted (6)
I believe the answer is:
Here is my best explanation:
'public official' is the definition.
(I've seen this before)
'never admits to being promoted' is the subsidiary indication.
'never' becomes 'nary' (I've seen this in other clues).
'admits' means one lot of letters goes inside another.
'being promoted' says the letters should be written backwards (going up, in a down clue).
'to' back-to-front is 'ot'.
'nary' going around 'ot' is 'notary'.
(Other definitions for notary that I've seen before include "One authorised to certify legal documents", "legal worker", "Person legally authorised to witness signatures", "One drawing up legal documents", "Certifier of deeds etc.", "- - public: official", "Legal official", "Official working on legal documents", "Official authorised to witness signing of documents" and "Person authorised to certify legal documents".)