Piece of music for choir at end of perfomance (7)
I believe the answer is:
chorale
'piece of music' is the definition.
'for choir at end of perfomance' is the wordplay.
'for choir' becomes 'choral'.
'at end of' says to take the final letters.
The last letter of 'perfomance' is 'e'.
'choral'+'e'='CHORALE'
(Other definitions for chorale that I've seen before include "Psalm or hymn tune" , "vocal music" , "Lutheran hymn-tune" , "Composition" , "hymn setting" .)