Localised death of cells (8)
I believe the answer is:
gangrene
'localised death of cells' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for gangrene that I've seen before include "Tissue decay from interrupted blood supply" , "It's mortifying" , "Death and decay of body tissue" , "Necrosis of body part" , "Necrotic tissue" .)