City's chapter gathering both sides in part of church (8)
I believe the answer is:
carlisle
'city's' is the definition.
(English city)
'chapter gathering both sides in part of church' is the wordplay.
'chapter gathering' becomes 'c' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'both sides' becomes 'RL' (abbreviations for left and right).
'in' is an insertion indicator.
'part of church' becomes 'aisle' (I've seen this before).
'rl' inserted into 'aisle' is 'arlisle'.
'c'+'arlisle'='CARLISLE'
Can you help me to learn more?
(Other definitions for carlisle that I've seen before include "Administrative centre of Cumbria" , "Cumbrian city where Royalists surrendered in 1645" , "See" , "County town of Cumbria" , "Cellars I turn to in Northern English city" .)