Upper part of the windpipe (6)
I believe the answer is:
larynx
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">upper part of the windpipe</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 larynx that I've seen before include "Location of vocal cords" , "part of neck" , "The formal voice box" , "The voice box, part of throat" , "Upper part of the windpipe" .)