Ancient harp (4)
I believe the answer is:
lyre
'ancient harp' 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 "Old musical instrument with strings in U-shaped frame" , "Ancient Greek harp" , "Ancient musical instrument - sounds mendacious" , "Instrument played by Orpheus" , "used to produce music" .)