Expert, authority (6)
I believe the answer is:
pundit
This clue is a double definition.
'expert' is the first definition.
(I've seen this in another clue)
'authority' is the second definition.
(I've seen this in another clue)
(Other definitions for pundit that I've seen before include "Talking expert" , "Learned authority" , "Pontificating expert" , "Maestro" , "Expert (sometimes self-appointed)" .)