Musical ornament (5)
I believe the answer is:
trill
'musical ornament' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for trill that I've seen before include "High-pitched warbling sound" , "Shrill warble" , "Sound of rapidly alternating notes" , "Warbling sound made by a songbird" , "Ornament" .)