Nasty oriental cat spat (11)
I believe the answer is:
altercation
'spat' is the definition.
(thesaurus)
'nasty oriental cat' is the wordplay.
'nasty' indicates anagramming the letters.
'oriental'+'cat'='orientalcat'
'orientalcat' anagrammed gives 'ALTERCATION'.
(Other definitions for altercation that I've seen before include "heated argument" , "One's argued" , "Noisy disagreement" , "Noisy quarrel" , "Spat" .)