Urgent order
I believe the answer is:
asap
'urgent order' 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 for urgent, quick as you can (4)" , "Notation meaning without delay, fast as you can" , "As soon as possible (abbrev.)" , "Notation or acronym meaning without avoidable delay" , "Initials notation meaning with all possible speed" .)