card up one's sleeve n. phr.,
informal Another help, plan, or argument kept back and produced if needed; another way to do something.
John knew his mother would lend him money if necessary, but he kept that card up his sleeve.
Bill always has a card up his sleeve, so when his first plan failed he tried another. Compare: ACE IN THE HOLE
2.
[TahlilGaran] English Idioms Dictionary ▲