Like some unpleasant air (5)
I believe the answer is:
stale
(Other definitions for stale that I've seen before include "Not fresh, being least" , "Boring" , "no longer bearing interest?" , "Unfresh" , "Least (anag.)" .)
I believe the answer is:
stale
(Other definitions for stale that I've seen before include "Not fresh, being least" , "Boring" , "no longer bearing interest?" , "Unfresh" , "Least (anag.)" .)