Feud great with NUM revitalised (8)
I believe the answer is:
argument
'feud' is the definition.
(thesaurus)
'great with num revitalised' is the wordplay.
'with' says to put letters next to each other.
'revitalised' indicates anagramming the letters.
'great' put after 'num' is 'numgreat'.
'numgreat' is an anagram of 'ARGUMENT'.
(Other definitions for argument that I've seen before include "Debate - disagreement" , "Contentious debate" , "Tiff" , "Heated debate" , "Quarrel, row" .)