Document about petty-officers being removed from office (7)
I believe the answer is:
deposed
'removed from office' is the definition.
(I've seen this before)
'document about petty-officers' is the wordplay.
'document' becomes 'deed' (deed is a kind of document).
'about' indicates putting letters inside.
'petty-officers' becomes 'pos' (I can't explain this - if you can you should give a lot more credence to this answer).
'deed' going around 'pos' is 'DEPOSED'.
'being' acts as a link.
Can you help me to learn more?
(Other definitions for deposed that I've seen before include "Forcibly removed from office" , "Thrown out" , "Forced out of office or power" .)