You can get fresh air out of them (5)
I believe the answer is:
doors
'you can get fresh air' is the definition.
I can't tell whether this defines the answer.
'of them' is the wordplay.
I cannot quite see how this works, but
'of' could be 'o' and 'o' is present in the answer.
The remaining letters 'dors' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'out' is the link.
Can you help me to learn more?
(Other definitions for doors that I've seen before include "Entrance barriers" , "Ways in and out" , "Openings" , "Barriers to entrances" , "Portals" .)