Despotic Italian rat to broadcast (12)
I believe the answer is:
totalitarian
'despotic' is the definition.
(thesaurus)
'italian rat to broadcast' is the wordplay.
'broadcast' indicates an anagram.
'italian'+'rat'+'to'='italianratto'
'italianratto' is an anagram of 'TOTALITARIAN'.
(Other definitions for totalitarian that I've seen before include "(Of states) extremely dictatorial" , "Tyrannical" , "Despotic" , "far from liberal" , "Allowing no opposition" .)