Some, with hindsight, say Castleroberts is nicer and don't allow any dissent (6)
I believe the answer is:
insist
'any dissent' is the definition.
The answer and definition can be both to do with communicating as well as being verbs in their base form.
Maybe there's an association between them I don't understand?
'some with hindsight say castleroberts is nicer and don't allow' is the wordplay.
'INSIST' is hidden backwards within the letters.
But, I'm uncertain how this is indicated.
Can you help me to learn more?
(Other definitions for insist that I've seen before include "Demand firmly" , "Put one's foot down" , "'Demand, make sure (6)'" , "Declare or demand emphatically" , "Continue to assert, maintain" .)