To hedge is to place a new bet that offsets part of an existing one. It lowers the range of results, so the best outcome is smaller and the worst is less bad. Hedging does not remove the bookmaker’s margin, and it usually costs something in expected value. It is often used when a multi leg bet has one selection left, or when odds on the other side have moved. A hedge can lock in a profit only when the prices allow it.
Example
A 10 unit bet on Team A at 5.00 would win 40 in profit. Before the final, a bet of 15 on Team B at 2.20 returns 33. If A wins the profit is 25 after both stakes. If B wins the profit is 8.