Zealous, impassioned (6)
I believe the answer is:
fervid
I believe this clue is a double definition.
'zealous' is the first definition.
(I've seen this before)
'impassioned' is the second definition.
(I know that impassioned can be written as fervid)
(Other definitions for fervid that I've seen before include "Intensely passionate" , "Fiery and passionate" , "Intensely enthusiastic" , "Zealous" , "Heated - vehement" .)