In the open air, not in a moving barrier (7)
I believe the answer is:
outdoor
'in the open air' is the definition.
(outdoor means out in the open air)
'not in a moving barrier' is the wordplay.
'not in' becomes 'out' ('out' is the opposite to 'in').
'a moving barrier' becomes 'door' (door is a kind of barrier. I am not sure about the 'moving' bit.).
'out'+'door'='OUTDOOR'
Can you help me to learn more?
(Other definitions for outdoor that I've seen before include "Taking place in the open air" , "exposed to the elements" , "Not done in the house" , "External" , "Located in the open air" .)