Respiratory tract (7)
I believe the answer is:
airways
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">respiratory tract</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that respiratory tract can be written as airways)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for airways that I've seen before include "Radio channels" , "Things fly along here" , "Ventilation passages" , "Inspiring passages" , "travel company" .)