Exit to the open air? (7)
I believe the answer is:
outdoor
'air?' is the definition.
(I have seen 'open air' mean 'outdoor' so perhaps 'air' could also mean 'outdoor')
'exit to the open' is the wordplay.
'exit' becomes 'door' (I've seen this in another clue).
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'the open' becomes 'out' (I've seen this in other clues).
'door' put after 'out' is 'OUTDOOR'.
(Other definitions for outdoor that I've seen before include "in the garden, say" , "Not done in the house" , "External" , "Open-air" , "exposed to the elements" .)