tipster

noun
1
a person who tells you, often in exchange for money, which horse is likely to win a race, so that you can bet on it and win money
مشاور شرط بندی, راهنمای پیش‌بینی, راهنمای شرط‌بندی
2
a person who gives information to the police about a crime or criminal
خبرچین, مخبر