Assault, assail (6)
I believe the answer is:
attack
I believe this is a double definition.
'assault' is the first definition.
(synonyms)
'assail' is the second definition.
(I know that assail can be written as attack)
(Other definitions for attack that I've seen before include "Act violently against or criticise strongly" , "mount an offensive" , "Fiercely criticise" , "Forward line" , "An assault or onslaught" .)