Maybe Indian uniform on back (5)
I believe the answer is:
hindu
'maybe indian' is the definition.
(many Hindus are Indian)
'uniform on back' is the wordplay.
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'on' says to put letters next to each other.
'back' becomes 'hind' (synonyms).
'u' after 'hind' is 'HINDU'.
(Other definitions for hindu that I've seen before include "Native of India" , "religious type" , "Devotee of Indian religion" , "Believer in South Asian religion" , "Follower of India's most popular religion" .)