Composer of the Brandenburg Concertos (4)
I believe the answer is:
bach
'composer of the brandenburg concertos' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for bach that I've seen before include "German organist and composer, d. 1750" , "JS --, baroque composer" , "musical great" , "J. S. --, baroque composer" , "endearing Welsh appellation" .)