Interrupt (a speaker) (6)
I believe the answer is:
heckle
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">interrupt a speaker</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for heckle that I've seen before include "Interrupt (a public speaker) with taunts" , "Shout abuse at, a speaker say" , "Mock or harangue speaker from crowd" , "disrupt meeting" , "Shout down (a politician)" .)