It needs to be scratched (4)
I believe the answer is:
itch
'it needs to be scratched' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for itch that I've seen before include "Irritate" , "longing for something" , "that's irritating" , "It must be scratched" , "Longing; anag. of 19" .)