Victory song transformed into alternative (9)
I believe the answer is:
variation
'alternative' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'victory song transformed into' is the wordplay.
'victory' becomes 'v'.
'song' becomes 'aria' (aria is a kind of song).
'transformed' indicates anagramming the letters.
'into' is an anagram of 'tion'.
'v'+'aria'+'tion'='VARIATION'
Can you help me to learn more?
(Other definitions for variation that I've seen before include "Departure from the norm" , "Discrepancy" , "Change, difference" , "Slight difference" , "Slight change" .)