Worshiper of Jah, informally (5)
I believe the answer is:
rasta
'worshiper of jah informally' 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 "sectarian worshipper" , "Often a Jamaican" , "Disciple" , "religious follower" , "One following religion" .)