Baby's plaything (6)
I believe the answer is:
rattle
'baby's plaything' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for rattle that I've seen before include "Toy for baby or football fan" , "Infant's toy" , "not to compose" , "Lively old song - Shake, . . . . . . and roll" , "Noisy toy and snake" .)