Shake toy (6)
I believe the answer is:
rattle
I believe this is a double definition.
'shake' is the first definition.
(rattling is a kind of shaking)
'toy' is the second definition.
(I've seen this before)
(Other definitions for rattle that I've seen before include "American viper" , "Baby's toy; sound of something loose" , "Baby's toy; irritate" , "Infant's toy" , "Shake - baby's toy" .)