Prepare popular backing section for classical music (5)
I believe the answer is:
opera
'classical music' is the definition.
(opera is a kind of classical music)
'prepare popular backing section' is the wordplay.
'section' indicates the answer is hidden within the clue.
'backing' says the letters should be written in reverse.
'arepo' is hidden in the letters of 'prepare popular'.
'arepo' backwards is 'OPERA'.
'for' is the link.
(Other definitions for opera that I've seen before include "One at the Met" , "Musical piece accompanying a stage drama or comedy" , "Musical play" , "Macbeth, say" , "eg Otello" .)