Pugilist unsportingly content with KO (4)

I believe the answer is:

stun

'ko' is the definition.
(thesaurus)

'pugilist unsportingly content with' is the wordplay.
'with' indicates a hidden word.
'STUN' is hidden within 'pugilist unsportingly content'.

(Other definitions for stun that I've seen before include "Numb with nuts" , "Shock into silence" , "Shock or astonish" , "'Shock, daze (4)'" , "Make dazed or numb" .)

I've seen this clue in The Guardian.

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