Part of circle backing opera in a pastoral paradise (7)
I believe the answer is:
arcadia
'a pastoral paradise' is the definition.
(I've seen this in another clue)
'part of circle backing opera' is the wordplay.
'part of circle' becomes 'arc' ('arc' is part of 'circle').
'backing' says the letters should be written in reverse.
'opera' becomes 'aida' (Verdi opera).
'aida' in reverse letter order is 'adia'.
'arc'+'adia'='ARCADIA'
'in' acts as a link.
(Other definitions for arcadia that I've seen before include "Poetically the home of songloving shepherds" , "such as Strephon enjoyed?" , "pastoral paradise" , "Idyllic country of song-loving shepards" , "Jumbo manufacturer" .)