Vocal organ (6)
I believe the answer is:
larynx
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">vocal organ</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that larynx is a type of vocal organ)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for larynx that I've seen before include "Air passage" , "part of neck" , "Where growls come from" , "box for speaker" , "it's essential to speak!" .)