Large study of participation in church services? (4,11)
I believe the answer is:
mass observation
'participation in church services?' is the definition.
The definition suggests a singular noun which matches the answer.
'large study' is the wordplay.
I cannot quite see how this works, but
'study' could be 'observation' (I've seen this before) and 'observation' is located in the answer.
The remaining letters 'mass' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for mass observation that I've seen before include "The study of social habits" , "familiar to practising Catholics?" , "Wartime project" .)