Swore Victor was in debt (5)
I believe the answer is:
vowed
'swore' is the definition.
(I've seen this in another clue)
'victor was in debt' is the wordplay.
'victor' becomes 'V' (phonetic alphabet: alpha, bravo, charlie etc.).
'was in debt' becomes 'owed' ('they owed' means 'they were in debt').
'v'+'owed'='VOWED'
(Other definitions for vowed that I've seen before include "Solemnly promised" , "Made a promise" , "took the pledge" , "Solemnly pledged" .)