A football player who is a skillful runner, passer, and kicker.
The definition of a triple threat is someone in a particular field who exhibits three skills that are necessary to excel.
An example of a triple threat is a football player in gridiron football who is great at passing, kicking and running.
An example of a triple threat is a person in theatre who can sing, dance and act.
A person who is expert or adept in three fields, skills, etc.