Dust or grime (4)
I believe the answer is:
dirt
This clue is a double definition.
'dust' is the first definition.
(thesaurus)
'grime' is the second definition.
(synonyms)
(Other definitions for dirt that I've seen before include "See 26" , "Muck" , "Obscenity" , "Grime - scandal" , "Scandalous information" .)