Church one left in no-frills area (8)
I believe the answer is:
basilica
'church' is the definition.
(type of large church)
'one left in no-frills area' is the wordplay.
'one left in no frills' becomes 'basilic' (I can't explain this - if you can you should believe this answer much more).
'area' becomes 'a' (maths abbreviation).
'basilic'+'a'='BASILICA'
Can you help me to learn more?
(Other definitions for basilica that I've seen before include "Large church building" , "Bails CIA out of the large church" , "Romanesque church" , "A large Christian church with two rows of columns (8)" , "Large (Roman Catholic) church" .)