Some of clergy readers forming circle (4)
I believe the answer is:
gyre
'circle' is the definition.
(I have seen 'Literary circle' mean 'gyre' so perhaps 'circle' could also mean 'gyre')
'some of clergy readers forming' is the wordplay.
'some of' indicates a hidden word.
'GYRE' is hidden within 'clergy readers forming'.
(Other definitions for gyre that I've seen before include "Literary circle" , "Whirl, spiral" , "'A series of concentric circles, as flower petals say (4)'" .)