Open, spacious (4)
I believe the answer is:
airy
This clue is a double definition.
'open' is the first definition.
(both can mean spacious)
'spacious' is the second definition.
(I've seen this before)
(Other definitions for airy that I've seen before include "Spacious; delicate" , "Spacious; nonchalant" , "Breezy" , "Flippant" , "(Of ideas) speculative" .)