Is prior to religious establishment panicking East End ministers? (9)

'is' is the definition.
The answer and definition can be both to do with fundamental existence as well as being verbs in their -s form.
Maybe they are linked in a way I don't understand?

'prior to religious establishment panicking east end ministers?' is the wordplay.
I cannot really understand how this works, but
'establishment' could be 'ce' (I've seen this in other clues) and 'ce' is present in the answer.
'east' could be 'e' (abbreviation) and 'e' is found within the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?