Victory on a river promises to be different (7)
I believe the answer is:
various
'different' is the definition.
(similar in meaning)
'victory on a river promises' is the wordplay.
'victory' becomes 'v'.
'on' is a charade indicator (letters next to each other).
'river' becomes 'r' (abbreviation for river).
'promises' becomes 'IOUs' (promises to pay a debt).
'v'+'a'+'r'+'ious'='VARIOUS'
'to be' is the link.
(Other definitions for various that I've seen before include "Disparate, diverse" , "Saviour (anag) -- assorted" , "Manifold" , "Saviour of many kinds" , "Saviour of different types" .)