Annoying mob's here to riot (10)
I believe the answer is:
bothersome
'annoying' is the definition.
(thesaurus)
'mob's here to riot' is the wordplay.
'riot' is an anagram indicator.
'mobs'+'here'+'to'='mobshereto'
'mobshereto' is an anagram of 'BOTHERSOME'.
(Other definitions for bothersome that I've seen before include "Irritating" , "causing trouble" , "Trying" , "A pain" , "Perplexing" .)