Grisly (8)
I believe the answer is:
gruesome
'grisly' is the definition.
(I know that grisly can be written as gruesome)
This is all the clue.
(Other definitions for gruesome that I've seen before include "terrible" , "Sickening, macabre" , "Repulsive, horrid" , "Extremely unpleasant" , "Revolting, filling one with horror and disgust" .)