Encircle and blockade (7)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
besiege
(Other definitions for besiege that I've seen before include "Surround - harass" , "Invest" , "Surround (a stronghold)" , "Encircle as a military tactic" , "Surround (a place) with hostile intent" .)