Activity (6)
I believe the answer is:
action
'activity' is the definition.
(I know that activity can be written as action)
This is the entire clue.
(Other definitions for action that I've seen before include "''. . . . . . speaks louder than words'' (6)" , "Accomplishment" , "Battle (in the law courts?)" , "Lawsuit; armed conflict" , "A judicial proceeding brought by one party against another" .)