Quarrel with composer about second note of major scale (6)
I believe the answer is:
breach
'quarrel' is the definition.
(thesaurus)
'composer about second note of major scale' is the wordplay.
'composer' becomes 'bach' (Bach is an example).
'about' means one lot of letters goes inside another.
'second note of major scale' becomes 're' (doh re me ...).
'bach' going around 're' is 'BREACH'.
'with' is the link.
(Other definitions for breach that I've seen before include "Gap (in a wall/barrier)" , "transgression" , "Non-observance" , "Gap in a wall or barrier" , "The breaking of a law or agreement" .)