One who informs bank worker (6)
I believe the answer is:
teller
I believe this is a double definition.
'one who informs' is the first definition.
(someone who 'tells')
'bank worker' is the second definition.
(Other definitions for teller that I've seen before include "who worked on the hydrogen bomb" , "Bank official to narrate the story" , "one who counts" , "Counter of votes or a bank employee" , "Election official" .)