up your sleeve

up (one's) sleeve

Of a plan or advantage, kept in secret so it can be utilized if and when it is required. A reference to cheating at a card game by hiding a favorable card up one's sleeve. My stamina is the ace up my sleeve for this race—the other runners don't stand a chance! I've got a few tricks up my sleeve if he decides to pursue legal action against me.
See also: sleeve, up
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

up your sleeve

(of a strategy, idea, or resource) kept secret and in reserve for use when needed.
See also: sleeve, up
Farlex Partner Idioms Dictionary © Farlex 2017
See also: