Harmless rattler
I believe the answer is:
maraca
'harmless rattler' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for maraca that I've seen before include "One of a pair of hollow pieces of wood or bone for Spanish dancing" , "Instrument made from a filled gourd" , "Percussion instrument played in pairs" , "'Hand-held percussion instrument, hand-held (6)'" , "Rattle used as a rhythm instrument" .)