Impressive manner mostly here shown by church (8)
I believe the answer is:
presence
This could be a double definition.
'impressive manner' is the first definition.
(I've seen this before)
'mostly here shown by church' is the second definition.
The answer is a location as well as being a singular noun. This is suggested by the definition.
Can you help me to learn more?
(Other definitions for presence that I've seen before include "Attendance; spirit" , "Aura; nearness" , "Physical attendance or imposing bearing" , "Demeanour" , "Imposing appearance" .)