Dry atmosphere (3)
I believe the answer is:
air
I believe this clue is a double definition.
'dry' is the first definition.
(airing is a kind of drying)
'atmosphere' is the second definition.
(I know that atmosphere can be written as air)
(Other definitions for air that I've seen before include "Atmosphere (of a melody?)" , "Region above the ground" , "If it's hot, it's boastful" , "that's inspired" , "Broadcast; gas" .)