Examine closely popular page penned by religious group (7)
I believe the answer is:
inspect
'examine closely' is the definition.
(I've seen this before)
'popular page penned by religious group' is the wordplay.
'popular' becomes 'in'.
'page' becomes 'p'.
'penned by' means one lot of letters goes inside another.
'religious group' becomes 'sect' (I've seen this before).
'p' placed inside 'sect' is 'spect'.
'in'+'spect'='INSPECT'
(Other definitions for inspect that I've seen before include "Ecamine closely" , "Look over carefully" , "Examine officially" , "Look at closely" , "Examine or survey" .)