Punjabi believer (4)
I believe the answer is:
'punjabi believer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sikh that I've seen before include "Indian believer" , "Religious adherent (eastern)" , "Follower of a religion founded in Punjab" , "Adherent of an Indian religion" , "An adherent of religion founded in the Punjab" .)