Ghastly ingrained dirt finally wiped (4)
I believe the answer is:
grim
'ghastly' is the definition.
(I know that ghastly can be written as grim)
'ingrained dirt finally wiped' is the wordplay.
'ingrained dirt' becomes 'grime' (I've seen this before).
'finally wiped' means to remove the last letter.
'grime' with its last letter removed is 'GRIM'.
(Other definitions for grim that I've seen before include "Harsh and merciless" , "Very serious, gloomy" , "Ghastly" , "Forbidding harsh and unpleasant" , "formidable" .)