In a game of baseball for example, "winsurance" are runs that are scored when you already have the lead in the game and are scored in the 7th inning or later. These are run that provide insurance that you will win the game.
The team was ahead 6 to 5 going into the 7th inning. They scored two more runs in the 8th inning to provide winsurance.
by drcft June 11, 2019