Lap up in game (4)
I believe the answer is:
pool
'game' is the definition.
(pool is a kind of game)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for pool that I've seen before include "Small lake" , "found in watery location" , "Mere - game" , "Ball game - piece of water" , "American game resembling snooker" .)