A game

American  

Or A-game,

noun

Informal.

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

   The candidate brought her A game to the debate.

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'A' game British  

noun

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

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Etymology

Origin of A game

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

Example Sentences

Guardiola's men have a game in hand against Crystal Palace but this could be a gameweek where the momentum and belief swings in the direction of Mikel Arteta's men.

From BBC

You’ll note that this was a game show about the news, in which the only prizes are bragging rights and an audience member’s chance to have Bill Kurtis provide the voice for the outgoing message on their phone’s answering service.

From Salon

‘They have cards in there. Want a game of rummy?’ she asks.

From Literature

I tried to make it sound like a game.

From Literature

“It’s a game changer in terms of building out a sustainable local news business,” he said.

From The Wall Street Journal