Soprano's brought in to transfer top notes (7)
I believe the answer is:
descant
'soprano's' is the definition.
(thesaurus)
'brought in to transfer top notes' is the wordplay.
'brought in to' is an insertion indicator.
'transfer' becomes 'decant' (to decant is to transfer to another container).
'top notes' becomes 's' (I am not sure about this - if you are sure you should believe this answer much more).
'decant' going around 's' is 'DESCANT'.
Can you help me to learn more?
(Other definitions for descant that I've seen before include "Melody sung or played above a basic melody" , "Highest range (eg of a 10)" , "Independent melody sung above a basic melody" , "Sung variation" , "Ornamental melody added above a theme" .)