Doze, initially exposing back of neck (4)
I believe the answer is:
nape
'back of neck' is the definition.
(I've seen this before)
'doze initially exposing' is the wordplay.
'doze' becomes 'nap' (I've seen this before**).
'initially' says to take the initial letters.
The first letter of 'exposing' is 'e'.
'nap'+'e'='NAPE'
(Other definitions for nape that I've seen before include "Scrag" , "It's a pane in the neck" , "Scruff of the neck" , "Girl personifying France" , "Back part of the neck" .)