Conductor and what he shook when much younger? (6)
I believe the answer is:
rattle
'conductor' is the definition.
(Rattle is an orchestra conductor)
I don't understand how the remainder of the clue works.
(Other definitions for rattle that I've seen before include "Clink; disconcert" , "Baby's toy - racket - disconcert" , "Child's noisy toy" , "American viper" , "Toy for child and football fan" .)