Besiege, assail (9)
I believe the answer is:
beleaguer
I believe this is a double definition.
'besiege' is the first definition.
(synonyms)
'assail' is the second definition.
(beleaguering is a kind of assailing)
(Other definitions for beleaguer that I've seen before include "Put in a very difficult position" , "Surround" , "put in a very difficult situation" .)