"Like, yesterday!" (4)
I believe the answer is:
asap
'like yesterday' 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 "yesterday?" , "'As quickly as you can, initially (4)'" , "Notation meaning without delay, fast as you can" , "Common acronym for quick-as-you-can" , "As soon as possible (abbrev.)" .)