Offensive weapons bringing malevolence into main thoroughfare (9)
I believe the answer is:
artillery
'offensive weapons' is the definition.
'artillery' can be an answer for 'weapons' (I've seen this before). I am not sure about the 'offensive' bit.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for artillery that I've seen before include "Army unit that uses big guns" , "Large guns for army in land war" , "Guns, cannons etc" , "Gunners" , "Large guns for use on land" .)