Hair loss (8)
I believe the answer is:
alopecia
'hair loss' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for alopecia that I've seen before include "Partial or complete absence of hair on the body" , "Loss of cover" , "Baldness (medical)" , "Loss of hair, baldness" , "23" .)