Immediately, in memos (4)
I believe the answer is:
asap
'immediately in memos' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for asap that I've seen before include "Notation meaning without delay, fast as you can" , "Notation meaning without delay, treat as urgent" , "'At the earliest moment, initially (4)'" , "Notation for urgent, quick as you can (4)" , "Notation for as quickly as you can" .)