Etiquette essential to high-profile actor's gossip-columnist? (8)

I believe the answer is:

protocol

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

'etiquette' is the definition.
(protocol is a kind of etiquette)

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

Can you help me to learn more?

(Other definitions for protocol that I've seen before include "Correct procedure" , "official rules" , "Code of behaviour" , "Official code of procedure" , "Etiquette with regard to rank or status" .)

I've seen this clue in The Irish Times.

Want a hint initially instead of a full solution? Install my app