Musical ending (4)
'musical ending' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for coda that I've seen before include "Musical finale" , "noted conclusion" , "Tailpiece" , "Closing passage of a piece of music" , "End piece written for a piece of music" .)
(Other definitions for outro that I've seen before include "bars closing" , "last lot of notes" , "Part that closes" , "Piece ending programme" .)