Fellows sold hens, disturbed composer (11)
I believe the answer is:
mendelssohn
'composer' is the definition.
(I have seen 'German composer' mean 'mendelssohn' so perhaps 'composer' could also mean 'mendelssohn')
'fellows sold hens disturbed' is the wordplay.
'fellows' becomes 'men' (fellow can mean a man).
'disturbed' indicates anagramming the letters (the order of letters is disturbed).
'sold'+'hens'='soldhens'
'soldhens' with letters rearranged gives 'delssohn'.
'men'+'delssohn'='MENDELSSOHN'
(Other definitions for mendelssohn that I've seen before include "Composer of Fingal's Cave overture, d. 1847" , "German romantic composer of orchestral and choral works, d. 1847" , "German composer of The Hebrides, d. 1847" , "Wedding March composer" , "German composer, Felix, d. 1847" .)