Writer not exactly sincere about very right-wing origin (9)

I believe the answer is:

scrivener

I'm a little stuck... Click here to teach me more about this clue!

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

'not exactly sincere about very right-wing origin' is the wordplay.
'not exactly' indicates an anagram.
'about' is a charade indicator (letters next to each other).
'very' becomes 'v' (abbreviation).
'right wing origin' becomes 'r' (I can't explain this - if you can you should believe this answer much more).
'sincere' put after 'v' is 'vsincere'.
'vsincere' with letters rearranged gives 'scrivene'.
'scrivene'+'r'='SCRIVENER'

Can you help me to learn more?

(Other definitions for scrivener that I've seen before include "Scribe" , "writer" , "Copyist" , "Notary" .)

I've seen this clue in The Guardian.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.