Takes the plunge putting Victor into the changed side (5)
I believe the answer is:
dives
'takes the plunge' is the definition.
(I've seen this in another clue)
'victor into the changed side' is the wordplay.
'victor' becomes 'V' (phonetic alphabet: alpha, bravo, charlie etc.).
'into' indicates putting letters inside.
'the changed' indicates anagramming the letters.
'side' is an anagram of 'dies'.
'v' inserted within 'dies' is 'DIVES'.
'putting' is the link.
(Other definitions for dives that I've seen before include "Drops steeply" , "Plunges head first" , "Rich man's" , "Disreputable resorts" , "Sleazy bars" .)