A note sent out by representatives (6)
I believe the answer is:
'representatives' is the definition.
(agent is a kind of representative)
'a note sent out by' is the wordplay.
'a note' becomes 'ag' (I can't justify this - if you can you should believe this answer much more).
'out' indicates an anagram (out can mean wrong or inaccurate).
'by' says to put letters next to each other.
'sent' is an anagram of 'ents'.
Can you help me to learn more?
(Other definitions for agents that I've seen before include "They do business on behalf of others" , "Sales reps" , "travelling salesmen" , "They act for others" , "They operate on behalf of others" .)