Leaders of town hall are supposed to provide idea (7)
I believe the answer is:
thought
'idea' is the definition.
('thought' can be a synonym of 'idea')
'leaders of town hall are supposed to' is the wordplay.
'leaders of' says to take the initial letters.
'are supposed to' becomes 'ought'.
The initial letters of 'town hall' is 'th'.
'th'+'ought'='THOUGHT'
'provide' acts as a link.
(Other definitions for thought that I've seen before include "Deliberated" , "Orwell's sort of police" , "Mental idea" , "Cogitated" , "Cogitation" .)