Component of early reed instrument (4)
I believe the answer is:
lyre
'instrument' is the definition.
(lyre is a kind of instrument)
'component of early reed' is the wordplay.
'component of' indicates a hidden word (I've seen this in other clues).
'LYRE' can be found hidden inside 'early reed'.
(Other definitions for lyre that I've seen before include "used to produce music" , "Type of harp" , "Instrument played by Orpheus" , "Harp used by ancient Greeks" , "Rely (anag.)" .)