Selective church returning positive response about circular letters (7)
I believe the answer is:
choosey
'selective' is the definition.
'church returning positive response about circular letters' is the wordplay.
'church' becomes 'ch' (common abbreviation).
'returning' says the letters should be written backwards.
'positive response' becomes 'yes' (I've seen this before).
'about' says to put letters next to each other.
'circular letters' becomes 'oo'.
'yes' reversed gives 'sey'.
'sey' after 'oo' is 'oosey'.
'ch'+'oosey'='CHOOSEY'
(Other definitions for choosey that I've seen before include "Discriminating" , "Picky" .)