Formal protest organised from Roman centres (12)

I believe the answer is:

remonstrance

I'm a little stuck... Click here to teach me more about this clue!

'formal protest' is the definition.
'remonstrance' can be an answer for 'protest' (I've seen this before). I am unsure of the 'formal' bit.

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for remonstrance that I've seen before include "Strong protest" , "petition" , "complaint" .)

I've seen this clue in The Times and The Sunday Times.

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