The definition of a clincher is a point or moment that settles a contest or decision.
An example of a clincher is a game that secures a baseball team's position in the World Series.
a person or thing that clinches; specif., a conclusive or decisive point, argument, act, etc.
- One that clinches, as:a. A nail, screw, or bolt for clinching.b. A tool for clinching nails, screws, or bolts.
- Informal A point, fact, or remark that settles something conclusively; a decisive factor.
From clinch + -er.