Orpheus' instrument (4)
I believe the answer is:
lyre
'orpheus' instrument' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lyre that I've seen before include "Music-maker" , "Ancient Greek harp" , "Ancient Greece harp" , "Instrument played by Orpheus" , "Ancient musical instrument - sounds mendacious" .)