Dirtiness (5)
I believe the answer is:
filth
'dirtiness' is the definition.
(filth is a kind of dirtiness)
This is the entire clue.
(Other definitions for filth that I've seen before include "Muck" , "Squalor" , "Carrion" , "Repulsive dirt" , "Disgusting dirt or obscenity" .)