A game

or A-game, a-game

noun

, Informal.

1. a person’s best effort, abilities, or achievement:

   The candidate brought her A game to the debate.

'A' game

noun

1. informal.
   one's best possible performance, esp in the phrase to bring or take one's 'A' game

Word History and Origins

Origin of A game¹

In reference to a sports contest, with the letter A indicating peak performance

Example Sentences

Some have suggested Letterman needed Leno as competition to bring his A-game night after night.

From The Daily Beast

Working with a guy like Željko is like playing basketball with an NBA star—you have to bring your A-game.

From The Daily Beast

Celebrate your birthday by showing those birds the three-men-to-a-game stunt.

From Project Gutenberg

Around the point of the hill to my right-where the herd had gone-a game trail dropped steeply to this bench.

From Project Gutenberg