Revolting Ruth is being arrogant (6)
I believe the answer is:
uppity
'being arrogant' is the definition.
(I've seen this before)
'revolting ruth' is the wordplay.
'revolting' becomes 'up' (rising up or revolting).
'ruth' becomes 'pity' (synonyms).
'up'+'pity'='UPPITY'
'is' is the link.
(Other definitions for uppity that I've seen before include "Difficult to control" , "Presumptuously arrogant" , "Not easily persuaded" , "Self-important, arrogant" , "Full of oneself" .)