Rabble-rouser (6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rabble-rouser</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for agitator that I've seen before include "activist" , "Demagogue" , "Person who stirs up trouble" , "Subversive person" , "Organiser" .)