Contagious skin infection (7)
I believe the answer is:
scabies
'contagious skin infection' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for scabies that I've seen before include "rash complaint?" , "Contagious skin disease that causes itching" , "Skin disease - "The Itch"" , "Contagious skin infection" , "Contagious skin disease causing itching" .)