Belligerent, truculent (10)
I believe the answer is:
aggressive
This clue is a double definition.
'belligerent' is the first definition.
(synonyms)
'truculent' is the second definition.
(similar in meaning)
(Other definitions for aggressive that I've seen before include "Pushy" , "Belligerent" , "Rudely hostile" , "Showing anger" , "Vigorous" .)