Domed section of a church (4)
I believe the answer is:
apse
'domed section of a church' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for apse that I've seen before include "where praetor sat" , "Peas (anag) - found in church" , "Projection to the east end of a church" , "Where the altar is usually found in a church" , "Semicircular recess in church" .)