Demagogue (6-6)
I believe the answer is:
rabble-rouser
'demagogue' is the definition.
(I know that demagogue can be written as rabble-rouser)
This is the entire clue.
(Other definitions for rabble-rouser that I've seen before include "One whipping up a crowd" , "Political agitator working on crowds" , "Person who stirs up feeling of mob" , "One who stirs up a crowd" , "Stirrer-up of a crowd" .)