Raid, incursion (6)
I believe the answer is:
inroad
This clue is a double definition.
'raid' is the first definition.
(inroad can mean a raid or attack)
'incursion' is the second definition.
(I know that inroad is a type of invasion)
(Other definitions for inroad that I've seen before include "Encroachment; hostile attack" , "Ordain (anag.)" , "One's intrusive" , "Incursion, raid" , "Sudden attack made into a country" .)