Excessive activity finished with force (9)
I believe the answer is:
overdrive
'excessive activity' is the definition.
'overdrive' can be an answer for 'activity' (I have seen 'Furious activity' mean 'overdrive' so perhaps 'activity' could also mean 'overdrive'). I'm unsure of the 'excessive' bit.
'finished with force' is the wordplay.
'finished' becomes 'over' (over can mean finished or ended).
'with' is a charade indicator (letters next to each other).
'force' becomes 'drive' (driving is a kind of forcing).
'over'+'drive'='OVERDRIVE'
Can you help me to learn more?
(Other definitions for overdrive that I've seen before include "Furious activity" , "It gets you going fast" , "Engine mechanism" , "state of intense activity" , "High gear; excessive activity" .)