Area of damaged tissue (6)
I believe the answer is:
lesion
'area of damaged tissue' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lesion that I've seen before include "Injury to living tissue" , "Abrasion" , "Harmful change in bodily tissue as from injury" , "A cut or wound in insole" , "Kind of injury in insole" .)