Forceful, impassioned (8)
I believe the answer is:
vehement
This clue is a double definition.
'forceful' is the first definition.
(I've seen this in another clue)
'impassioned' is the second definition.
(I've seen this in another clue)
(Other definitions for vehement that I've seen before include "Forceful, ardent" , "Even them being intense, showing strong feeling" , "Forcefully emphatic" , "Energetic" , "Zealously forceful" .)