Tipster (noun)

A person who gives insider information or advice, especially about horse racing or sports betting.

Origin:

First recorded in 1820–30, tipster is from the word tip ("a piece of advice, especially about a horse race") + -ster.

Examples:

1. He was known to be a reliable tipster for horse racing.
2. The tipster promised to give him exclusive information about the upcoming game.
3. Tipster's advice led to the man winning a lot of money.
4. The tipster had an impressive track record of correctly predicting the outcomes of sports events.
5. He paid a lot of money to subscribe to the tipster's exclusive service.