Irritation of the skin (4)
I believe the answer is:
itch
'irritation of the skin' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for itch that I've seen before include "Strong desire to do something" , "Long" , "Constant desire" , "Impatient desire (colloq.)" , "following seven years in union?" .)