Quickly, in memos (4)
I believe the answer is:
asap
'quickly 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 "Common acronym for quick-as-you-can" , "Notation or acronym meaning without avoidable delay" , "'As quickly as you can, initially (4)'" , "Notation meaning without delay, fast as you can" , "Notation for urgent, quick as you can (4)" .)