Attack a sailor in report (7)
I believe the answer is:
assault
'attack' is the definition.
(I know that assault is a type of attack)
'a sailor in report' is the wordplay.
'sailor' becomes 'salt' (salt is a kind of sailor).
'in report' shows a homophone (sound like) (ie reportedly, we hear).
'salt' sounds like 'ssault'.
'a'+'ssault'='ASSAULT'
(Other definitions for assault that I've seen before include "Attack suddenly" , "Violent attack in action or words" , "set about" , "Sort of course" , "Physical attack" .)