Irrupt (6)
I believe the answer is:
invade
'irrupt' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for invade that I've seen before include "Enter illegally" , "Attack, trespass on" , "Penetrate harmfully, country or body" , "Enter another's territory" , "Enter by force so as to conquer" .)