Single man, composer, retired character (8)
I believe the answer is:
bachelor
'single man' is the definition.
'composer retired character' is the wordplay.
'composer' becomes 'bach' (Bach is an example).
'retired' says the letters should be written backwards.
'character' becomes 'role' ('role' can be a synonym of 'character'**).
'role' in reverse letter order is 'elor'.
'bach'+'elor'='BACHELOR'
(Other definitions for bachelor that I've seen before include "Single person" , "Non-married male" , "leading man at start of Wedding Cantata" , "Unmarried male" , "Single man" .)