Musical locks (4)
I believe the answer is:
hair
I believe this clue is a double definition.
'musical' is the first definition.
(1960s musical)
'locks' is the second definition.
(locks can mean hair)
(Other definitions for hair that I've seen before include "Human head covering" , "It grows from the skin" , "Tresses" , "1960s' rock musical with nudity" , "Filament growing from the skin" .)