Agitate childishly? (6)
I believe the answer is:
rattle
'agitate' is the definition.
(rattling is a kind of agitating)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for rattle that I've seen before include "rabbit" , "Warning given by deadly snake" , "worry" , "Clatter or bang" , "Put out" .)