Unexpectedly it curtails retaining expression of individuality following religious practice (11)
I believe the answer is:
ritualistic
'unexpectedly it curtails retaining expression of individuality following religious' is the definition.
I can't tell whether this defines the answer.
'practice' is the wordplay.
I cannot really understand how this works, but
'practice' could be 'ritual' (ritual is a kind of practice) and 'ritual' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ritualistic that I've seen before include "Invariably performed in the same way" , "Involving religious ceremony" , "Relating to prescribed ceremony" , "Invariably done in the same way" , "Like religious services" .)