Naivety of establishment at some point concealing church (9)
I believe the answer is:
innocence
'naivety of establishment' is the definition.
'innocence' can be an answer for 'naivety' (innocence is a kind of naivety). I'm unsure of the 'of establishment' bit.
'at some point concealing church' is the wordplay.
'at' becomes 'in'.
'some point' becomes 'nonce' (I can't justify this - if you can you should give a lot more credence to this answer).
'concealing' is an insertion indicator.
'church' becomes 'ce' (abbreviation for Church of England).
'nonce' enclosing 'ce' is 'nocence'.
'in'+'nocence'='INNOCENCE'
Can you help me to learn more?
(Other definitions for innocence that I've seen before include "lack of conviction" , "Guilelessness" , "Uncorrupted state" , "Naivety" , "Honesty" .)