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

“What I like so much about college football is the regionality of it, where every time you watch a game you get a little glimpse into a pocket of the country,” Elm said.

From The Wall Street Journal

Mattel sells a game called Pictionary vs.

From Los Angeles Times

Former Australia coach Darren Lehmann said England should have "had a better back-up plan" if they think "have made the wrong call" with Bashir but he deserves a game with the Ashes lost.

From BBC

Since then, Travis has worked as a game show host, an actor and an executive producer.

From BBC

Mavericks prodigy Cooper Flagg once again stole the show, with the gifted 19-year-old No.1 draft pick scoring a game high 33 points with nine rebounds and nine assists.

From Barron's