Bracing air over area (5)
I believe the answer is:
ozone
'bracing air' is the definition.
(I've seen this before)
'over area' is the wordplay.
'over' becomes 'o' (cricket abbreviation).
'area' becomes 'zone' (zone is a kind of area).
'o'+'zone'='OZONE'
(Other definitions for ozone that I've seen before include "Sea air; bleaching agent" , "Trioxygen" , "Form of oxygen, O3" , "Atmospheric gas shielding us from ultraviolet radiation" , "Less common form of oxygen" .)