Pronto, in a memo (4)
I believe the answer is:
asap
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pronto in a memo</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for asap that I've seen before include "Notation-acronym meaning without delay" , "Initials notation meaning with all possible speed" , "yesterday?" , "Notation for urgent, quick as you can (4)" , "At one's earliest convenience" .)