Rich performance with old singers (5)
I believe the answer is:
choir
'singers' is the definition.
(group of singers)
'rich performance with old' is the wordplay.
'performance with' is an anagram indicator.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'rich' anagrammed with 'o' gives 'CHOIR'.
(Other definitions for choir that I've seen before include "Religious chorus, perhaps" , "set of singers" , "Chorus in church" , "warblers" , "Vocal group" .)