In midst of song rotter finds paradise (7)
I believe the answer is:
arcadia
'paradise' is the definition.
(I have seen 'rural paradise' mean 'arcadia' so perhaps 'paradise' could also mean 'arcadia')
'in midst of song rotter' is the wordplay.
'in midst of' indicates putting letters inside.
'song' becomes 'aria' (piece of music in an opera).
'rotter' becomes 'cad' (a cad is a dishonourable person).
'aria' placed around 'cad' is 'ARCADIA'.
'finds' is the link.
(Other definitions for arcadia that I've seen before include "Idealised Greek district" , "pastoral paradise" , "Ideal rustic paradise" , "Tom Stoppard play" , "Jumbo manufacturer" .)