Cathedral section (4)
I believe the answer is:
nave
'cathedral section' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nave that I've seen before include "Central part of church" , "Main body of a church" , "Take no risks" , "The hub of a wheel, or body of church" , "Part of a church sounds roguish" .)