Getting into the office? (9)

I believe the answer is:

accession

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

'getting' is the definition.
(accession is a kind of getting)

I don't understand the rest of the clue.

(Other definitions for accession that I've seen before include "New item added to a library or museum" , "Act of taking up office" .)

I've seen this clue in The Sun.

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.