Informants at the bank (7)

I believe the answer is:

tellers

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'informants' is the definition.
The definition and answer can be both people as well as being plural nouns.
Maybe there's a link between them I don't understand?

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for tellers that I've seen before include "who are recounting" , "Bank employees" , "Bank cashiers" , "Vote counters" .)

I've seen this clue in The Daily Express.

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