Ingrained muck (5)
I believe the answer is:
grime
(Other definitions for grime that I've seen before include "Engrained dirt" , "Ingrained dirt" , "Muck" , "an ingrained phenomenon" , "Soot" .)
I believe the answer is:
grime
(Other definitions for grime that I've seen before include "Engrained dirt" , "Ingrained dirt" , "Muck" , "an ingrained phenomenon" , "Soot" .)