Orpheus's instrument (4)
I believe the answer is:
lyre
'orpheus's instrument' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lyre that I've seen before include "Music-maker" , "Old musical instrument with strings in U-shaped frame" , "Ancient Greece harp" , "Harp used by ancient Greeks" , "Early harp" .)