Conservative following the correct route for large hall (9)
I believe the answer is:
concourse
'large hall' is the definition.
'concourse' can be an answer for 'hall' (concourse is a kind of hall). I'm not certain of the 'large' bit.
'conservative following the correct route' is the wordplay.
'conservative' becomes 'C' (UK political abbreviation).
'following the correct route' becomes 'on course' (I've seen this before).
'c'+'oncourse'='CONCOURSE'
'for' is the link.
Can you help me to learn more?
(Other definitions for concourse that I've seen before include "Open area in or outside a public building" , "A gathering of people" , "Large open space in, eg, railway station" , "part of airport" , "spacious area?" .)