Singers provide rich variety round circle (5)
I believe the answer is:
choir
'singers' is the definition.
(group of singers)
'rich variety round circle' is the wordplay.
'variety' indicates anagramming the letters.
'round' is an insertion indicator.
'circle' becomes 'O' (O is a circle).
'rich' is an anagram of 'chir'.
'chir' going around 'o' is 'CHOIR'.
'provide' is the link.
(Other definitions for choir that I've seen before include "Large group of singers" , "Organised group of singers" , "set of singers" , "People in church" , "Band of singers" .)