The Queen inhales the air (5)
I believe the answer is:
ether
'the air' is the definition.
(literary term for the air or sky)
'the queen inhales' is the wordplay.
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'inhales' indicates putting letters inside (inserted letters are inhaled).
'the' placed within 'er' is 'ETHER'.
(Other definitions for ether that I've seen before include "Solvent; clear sky (poet.)" , "Formerly an anaesthetic" , "Anaesthetic; clear sky (poetic)" , "Some were put out by this" , "Colourless liquid used as a solvent" .)