Ethereal (4)
I believe the answer is:
airy
'ethereal' is the definition.
(I know that ethereal can be written as airy)
This is the entire clue.
(Other definitions for airy that I've seen before include "Spacious; delicate" , "Fanciful" , "Light, delicate" , "Light and spacious" , "Delicate, casual" .)