The clerk will notify you (6)
I believe the answer is:
teller
'the clerk' is the definition.
(I've seen this before)
'will notify you' is the wordplay.
'will' means one lot of letters go next to another (I've seen this in other clues).
'notify' becomes 'tell' (I've seen this before).
'you' becomes 'er' (I am not sure about this - if you are sure you should believe this answer much more).
'tell'+'er' is 'TELLER'.
Can you help me to learn more?
(Other definitions for teller that I've seen before include "Election official" , "Narrator and bank clerk" , "One who instructs" , "Edward ---, physicist; vote-counter" , "one reckons" .)