Offensively self-assertive (9)
I believe the answer is:
bumptious
'offensively self-assertive' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for bumptious that I've seen before include "Offensively self-assertive" , "Irritatingly self-assertive" , "pushy?" , "self-important" .)