Fluff, down (4)
I believe the answer is:
fuzz
I believe this clue is a double definition.
'fluff' is the first definition.
(thesaurus)
'down' is the second definition.
(thesaurus)
(Other definitions for fuzz that I've seen before include "Indistinctness" , "Frizzy hair; blurred image" , "Police - fluff" , "Adolescent beard - the police" , "Met, perhaps" .)