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

Within hours, copies were multiplying, leading to a game of cat-and-mouse.

From The Wall Street Journal

Because the evidence of these 90 minutes tells us that to lose Kane for a game of greater consequence would be a major issue.

From BBC

In 218 games for Detroit, Ivey averaged 14.8 points, 3.5 rebounds and four assists in 27.9 minutes a game.

From Los Angeles Times

Back then, the miscues included officials mistakenly awarding a team an extra timeout, a helmet-to-helmet that went uncalled despite knocking a receiver unconscious, and a game with so many questionable flags that announcer Al Michaels dubbed the fans’ protests the “loudest manure chant” he had ever heard.

From The Wall Street Journal

I need to choose a game I can actually win, so that Dad doesn’t need to buy more tickets to get me the prize he’s hell-bent on making sure I get.

From Literature