PDQ kin (4)
I believe the answer is:
asap
'pdq kin' 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 with minimum delay" , "'As quickly as you can, initially (4)'" , "'At the earliest moment, initially (4)'" , "Notation meaning without delay, treat as urgent" , "Notation meaning without delay, fast as you can" .)