Back of neck (4)
I believe the answer is:
nape
'back of neck' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for nape that I've seen before include "Scruff of the neck" , "Here's a hairline" , "Girl personifying France" , "Back part of the neck" , "It's a pane in the neck" .)