Advance when yours truly leaves job (4)
I believe the answer is:
post
'job' is the definition.
(post is a kind of job)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for post that I've seen before include "employment" , "Publish' mail' job" , "Publicly display; send" , "trading establishment" , "Mail; office" .)