Insulting attack (9)
I believe the answer is:
offensive
I believe this is a double definition.
'insulting' is the first definition.
(similar in meaning)
'attack' is the second definition.
(similar in meaning)
(Other definitions for offensive that I've seen before include "Causing anger or resentment" , "See 8" , "Aggressive campaign" , "drive" , "Likely to upset" .)