A tour riots disrupted? That's untrue (10)
I believe the answer is:
traitorous
'untrue' is the definition.
(thesaurus)
'a tour riots disrupted?' is the wordplay.
'disrupted?' is an anagram indicator.
'a'+'tour'+'riots'='atourriots'
'atourriots' is an anagram of 'TRAITOROUS'.
'that's' acts as a link.
(Other definitions for traitorous that I've seen before include "Unfaithful" , "committing treachery" , "Disloyal" , "throwing down the Emperor?" , "Betraying" .)