Open or unopened milk container? (4)
I believe the answer is:
airy
'open' is the definition.
(both can mean spacious)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for airy that I've seen before include "Breezy" , "Ethereal" , "Delicate; dismissive" , "Well-ventilated; casual" , "affecting nonchalance" .)