Endlessly support excessively distant diplomatic code? (8)

I believe the answer is:

protocol

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'diplomatic code?' is the definition.
(I've seen this in another clue)

I don't understand the rest of the clue.

(Other definitions for protocol that I've seen before include "Approved procedure" , "customs" , "Procedure or system of rules" , "Code of conduct, etiquette" , "Official code of procedure" .)

I've seen this clue in The Telegraph.

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