Circuits almost become void (4)
I believe the answer is:
laps
'circuits' is the definition.
('lap' can be a synonym of 'circuit')
'almost become void' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'become void' becomes 'lapse' (I've seen this in another clue).
'lapse' with its last letter taken away is 'LAPS'.
(Other definitions for laps that I've seen before include "Circuits of a racetrack" , "Scoops up with the tongue" , "Pals doing rounds of the track" , "Circuits of track" , "Drinks; circuits" .)