Secretary birds for errand-boys (10)

I believe the answer is:

messengers

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'secretary birds' is the definition.
The definition and answer can be both people as well as being plural nouns.
Perhaps they are linked in a way I don't understand?

I can't explain the rest of the clue.

Can you help me to learn more?

(Another definition for messengers that I've seen is " Bringers of news".)

I've seen this clue in the Sydney Morning Herald.

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