The phrase "a safe bet" refers to something that is very likely to happen or be successful. Some synonyms for this phrase include sure thing, certainty, guaranteed, reliable, foolproof, and surefire. These words all indicate a high level of confidence in an outcome or decision. Other phrases that convey a similar meaning include "in the bag," "a shoo-in," and "a slam dunk." It's important to note that while these phrases imply a low level of risk, there is always some uncertainty in any situation. Regardless, using these phrases can convey confidence and certainty in your language and decision-making.