Interoffice note (4)
I believe the answer is:
memo
'interoffice note' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for memo that I've seen before include "Brief note, usually between co-workers" , "Short note or message" , "In brief, a note of events" , "It will remind" , "diplomatic communication?" .)