Upper windpipe (6)
I believe the answer is:
larynx
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">upper windpipe</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 larynx that I've seen before include "box for speaker" , "part of pipe" , "Where growls come from" , "Upper part of the windpipe" , "Air passage" .)