Cancel, as a check (4)
I believe the answer is:
void
'cancel as a check' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for void that I've seen before include "Gap, absence" , "Containing nothing or not legally binding" , "Empty space or legally invalid" , "Not valid, empty space" , "Empty space or vacuum" .)