Disconcert concert-master (6)
I believe the answer is:
rattle
'disconcert' is the definition.
(thesaurus)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for rattle that I've seen before include "Noisy baby's toy" , "Disconcert - English conductor, b. 1955" , "Infant's toy" , "Gurgling sound in throat" , "Lively old song - Shake, . . . . . . and roll" .)