Mouldy-smelling (5)
I believe the answer is:
musty
I believe this is a double definition.
'mouldy' is the first definition.
(I know that mouldy can be written as musty)
'smelling' is the second definition.
(I have seen 'Stale smelling ' mean 'musty' so perhaps 'smelling' could also mean 'musty')
(Other definitions for musty that I've seen before include "Mouldy; outdated" , "Smelling stale or damp" , "Stale and dank" , "Stale and stuffy" , "Mouldy; stale-smelling" .)