'A' game
'A' game
n
chiefly informal US and Canadian one's best possible performance, esp in the phrase to bring or take one's 'A' game
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014