Drink: get one round ahead (3)
I believe the answer is:
Here is my best explanation:
I believe this is a double definition.
'drink' is the first definition.
(lapping is a kind of drinking)
'get one round ahead' is the second definition.
(in motor racing, for example)
(Other definitions for lap that I've seen before include "Course circuit", "Lick", "Once around the course", "Scoop up with the tongue", "Circuit; drink", "Use tongue to drink; circuit", "One round of the track", "400 metres, typically", "Drink; lick" and "One round of the course".)