Composer's three notes hard to follow (4)
I believe the answer is:
bach
'composer's' is the definition.
(Johann Sebastian Bach)
'three notes hard to follow' is the wordplay.
'three notes' can mean three substitutions for 'note'.
'note' becomes 'b' (musical note).
'note' becomes 'a' (musical note).
'note' becomes 'c' (musical note).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'to follow' says to put letters next to each other.
'b'+'a'+'c'+'h'='BACH'
(Other definitions for bach that I've seen before include "Goldberg Variations composer, d. 1750" , "Musical family" , "musical great" , "JS --, baroque composer" , "Brandenburg Concertos composer, d. 1750" .)