He wrote notes maybe covering for elder, it’s said (4)
I believe the answer is:
bach
'he wrote notes' is the definition.
(classical composer Johannes Sebastian Bach)
'maybe covering for elder it's said' is the wordplay.
'maybe covering for elder' becomes 'bark' (covering for an elder tree).
'it's said' shows a homophone (sound like).
'bark' is a homophone of 'BACH'.
(Other definitions for bach that I've seen before include "German composer, who had twenty children, d.1750" , "German organist and composer, d. 1750" , "Welsh term of endearment" , "Musical family" , "Johann Sebastian . . . . , great composer (4)" .)