Zealous right in a depression (6)
I believe the answer is:
ardent
'zealous' is the definition.
('ardent' can be a synonym of 'zealous')
'right in a depression' is the wordplay.
'right' becomes 'r' (common abbreviation).
'in' indicates putting letters inside.
'depression' becomes 'dent' ('dent' can be a synonym of 'depression'**).
'a'+'dent'='adent'
'r' put within 'adent' is 'ARDENT'.
(Other definitions for ardent that I've seen before include "Intensely enthusiastic" , "Passionate and glowing" , "Enthusiastic, eager" , "Ranted, being impassioned" , "Fervid" .)