Ann’s chum became a famous composer (8)
I believe the answer is:
schumann
'a famous composer' is the definition.
'schumann' can be an answer for 'composer' (I've seen this before). I am unsure of the 'a famous' bit.
'ann's chum became' is the wordplay.
'became' indicates anagramming the letters (I've seen 'become' mean this).
'anns'+'chum'='annschum'
'annschum' anagrammed gives 'SCHUMANN'.
Can you help me to learn more?
(Other definitions for schumann that I've seen before include "Robert -, nineteenth century German composer" , "German composer, 1810-56" , "Robert --, German romantic composer" , "German barman" , "Nan, chums go for this composer" .)