Triumph by right though it may be indecisive (5,7)
I believe the answer is:
moral victory
'it may be indecisive' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'triumph by right though' is the wordplay.
'triumph' becomes 'victory' (synonyms).
'by' is a charade indicator (letters next to each other).
'right though' becomes 'moral' (similar in meaning. I am not sure about the 'though' bit.).
'victory' after 'moral' is 'MORAL VICTORY'.
Can you help me to learn more?
(Another definition for moral victory that I've seen is " Defeat with redeeming features".)