Inhaled and exhaled air (6)
I believe the answer is:
breath
'inhaled and exhaled air' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for breath that I've seen before include "Air in an out of the lungs" , "Slight breeze; life" , "Air that's inhaled and exhaled" , "An inhalation and exhalation" , "Slight movement of air" .)