Sound like a baby’s toy (6)
I believe the answer is:
This clue is a double definition.
'sound' is the first definition.
(I know that rattle is a type of sound)
'a baby's toy' is the second definition.
(I've seen this in another clue)
'like' acts as a link.
(Other definitions for rattle that I've seen before include "Infant's toy" , "Baby's toy; sound of loose part" , "Noisy toy and snake" , "Make nervous; child's toy" , "not to compose" .)