Unprincipled victor gets rid of half promissary notes (7)

I believe the answer is:

vicious

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'unprincipled' is the definition.
(thesaurus)

'victor gets rid of half promissary notes' is the wordplay.
'gets rid of half' suggests halving the letters.
'promissary notes' becomes 'ious' (I Owe You notes. I am not sure about the 'promissary' bit.).
'victor' with half the letters taken is 'vic'.
'vic'+'ious'='VICIOUS'

Can you help me to learn more?

(Other definitions for vicious that I've seen before include "Savage and strongly spiteful" , "Brutal, savage and dangerous" , "Malicious - degenerate" , "Deliberately nasty" , "Strongly spiteful and dangerous" .)

I've seen this clue in The Irish News.

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