Trachea (8)
I believe the answer is:
windpipe
'trachea' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for windpipe that I've seen before include "The trachea is another name for this breathing passage" , "The trachea, less formally" , "Common name for the trachea" , "It conveys air from the larynx to the lungs" , "Principal passage by which air reaches lungs" .)