Change one's locks? (3)
I believe the answer is:
dye
'change one's locks?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dye that I've seen before include "Colouring material" , "Colouring matter" , "Colouring; sounds like fade" , "Colour by dipping in liquid" , "Hair colouring" .)