Hairstyle with a coil or knot at the back of the head (7)
I believe the answer is:
chignon
(Other definitions for chignon that I've seen before include "Coil of hair at the back of the head" , "Roll of hair worn at the back of the head" , "Roll of hair worn at the nape" , "Topknot" , "Arrangement of coil of hair" .)