The person giving orders is the clerk (6)

I believe the answer is:

teller

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'clerk' is the definition.
(I've seen this before)

I don't understand the rest of the clue.

(Other definitions for teller that I've seen before include "Bank official or reporter" , "Counter of votes or a bank employee" , "Edward ---, physicist; vote-counter" , "One who instructs" , "Bank official or narrator" .)

I've seen this clue in the Evening Standard.

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