Mouldy-smelling (5)
I believe the answer is:
musty
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">mouldy</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">smelling</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I have seen 'Stale smelling ' mean 'musty' so perhaps 'smelling' could also mean 'musty')</span><br/ ><br/ ></span>
(Other definitions for musty that I've seen before include "Mouldy; outdated" , "Smelling stale or damp" , "Stale and dank" , "Stale and stuffy" , "Mouldy; stale-smelling" .)