Band tour on back of success on-line? (6)
I believe the answer is:
stripe
'band' is the definition.
(synonyms)
'tour on back of success on-line?' is the wordplay.
'tour' becomes 'trip' (I've seen this in other clues).
'on' says to put letters next to each other.
'back of' suggests the final letters.
'on-line?' becomes 'e' (abbreviation for electronic, e.g. in ecommerce).
The last letter of 'success' is 's'.
'trip' put after 's' is 'strip'.
'strip'+'e'='STRIPE'
(Other definitions for stripe that I've seen before include "Priest (anag)" , "promotion, maybe" , "Length of material, maybe showing rank" , "Military rank indicator" , "Line of different colour - indicator of rank" .)