Security devices for the hair (5)
I believe the answer is:
locks
This clue is a double definition.
'security devices' is the first definition.
(I've seen this in another clue)
'the hair' is the second definition.
(locks can mean hair)
'for' is the link.
(Other definitions for locks that I've seen before include "Fastens - hair" , "Secures; person's hair" , "Securely fixes" , "Canal features" , "raising devices for sailors" .)