Harp ancestor (4)
I believe the answer is:
lyre
'harp ancestor' 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" , "Instrument played by Orpheus" , "Old musical instrument with strings in U-shaped frame" , "Ancient musical instrument - sounds mendacious" , "Old instrument, like a harp" .)