Person on a soapbox (6)
I believe the answer is:
orator
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">person on a soapbox</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for orator that I've seen before include "I declaim" , "One addressing" , "A gifted public speaker" , "Eloquent public speaker" , "One who holds forth" .)