With cry, Teresa upset office worker (9)
I believe the answer is:
secretary
'office worker' is the definition.
'secretary' can be an answer for 'worker' (secretary is a kind of worker). I am not sure about the 'office' bit.
'with cry teresa upset' is the wordplay.
'with' is a charade indicator (letters next to each other).
'upset' indicates an anagram.
'cry'+'teresa' is 'cryteresa'.
'cryteresa' with letters rearranged gives 'SECRETARY'.
Can you help me to learn more?
(Other definitions for secretary that I've seen before include "Office assistant" , "Ambassador's assistant" , "PA" , "Assistant to handle correspondence" , "senior civil servant" .)