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.

---

'A' game British  

noun

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

---

Etymology

Origin of A game

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

Example Sentences

“I don’t think he’s been on the field yet, but he’s swinging from both sides, he’s running, playing catch, and all of that stuff. So, he’s progressing nicely. Still, obviously a ways away from playing in a game, but it’s been really good to see his kind of progression.”

From Los Angeles Times

A “Game of Thrones” movie is in development at Warner Bros. written by “House of Cards” showrunner Beau Willimon, The Times has confirmed.

From Los Angeles Times

Trae Young has yet to play a game for the Washington Wizards.

From Los Angeles Times

The four-time All Star has, however, already been ejected from a game as a member of the team.

From Los Angeles Times

As a game, it doesn't feel like we've got that balance right.

From BBC