Impostor, an Asian priest (6)
I believe the answer is:
shaman
'asian priest' is the definition.
'shaman' can be an answer for 'priest' (shaman is a kind of priest). I am not sure about the 'asian' bit.
'impostor an' is the wordplay.
'impostor' becomes 'sham' ('sham' can be a synonym of 'impostor').
'sham'+'an'='SHAMAN'
Can you help me to learn more?
(Other definitions for shaman that I've seen before include "religious figure" , "who practises a form of spiritualism?" , "Tribal medicine man" , "Sorcerer" , "Spiritual healer" .)