Out of doors, old songwriter may do so (4-3)
I believe the answer is:
open-air
'out of doors' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
(Other definitions for open-air that I've seen before include "Outdoor" , "not below roof" , "Exposed to the elements" , "Alfresco" , "outside" .)