Rotten, almost vicious, bossy and intrusive (9)
I believe the answer is:
officious
'intrusive' is the definition.
(similar in meaning)
'rotten almost vicious' is the wordplay.
'rotten' becomes 'off' (rotten food is 'off').
'almost' means to remove the first letter.
'vicious' with its initial letter taken away is 'icious'.
'off'+'icious'='OFFICIOUS'
'bossy and' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for officious that I've seen before include "Assertively meddling" , "Assertively interfering" , "Offensively meddlesome" , "Too ready to offer help and advice when it's not wanted" , "Domineering" .)