Believer in Jah (5)
I believe the answer is:
rasta
'believer in jah' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rasta that I've seen before include "worshipper of Haile Selassie" , "sectarian worshipper" , "Member of religious group" , "Follower of Rastafarianism" , "Often a Jamaican" .)