Perfectly framing repeated note, a piece of music (7)
I believe the answer is:
toccata
'piece of music' is the definition.
(I know that toccata is a type of piece of music)
'perfectly framing repeated note a' is the wordplay.
'perfectly' becomes 'to a t' ('to a T' or 'to a tee' can mean perfectly).
'framing' means one lot of letters goes inside another (inserted letters are framed by the outside letters).
'repeated' indicates the doubling of some letters.
'note' becomes 'c' (musical note).
'c' doubled is 'cc'.
'toat' placed around 'cc' is 'toccat'.
'toccat'+'a'='TOCCATA'
(Other definitions for toccata that I've seen before include "Series of musical runs and chords before a fugue" , "Musical composition with rapid elaborate runs" , "Baroque keyboard composition" , "Flashy piece of music" , "Touching piece" .)