Hostile incursion (6)
I believe the answer is:
inroad
'hostile incursion' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for inroad that I've seen before include "One's intrusive" , "Encroachment; hostile attack" , "Sudden attack made into a country" , "Ordain (anag.)" , "Incursion, raid" .)