have a card up (your) sleeve

to have an advantage that other people do not know about.

I still had a card up my sleeve in the form of a letter from his father.

• put back on the rails
• put back on track
• put back up
• put behind
• put behind someone
• put behind something
• put behind you
• put best foot forward
• put cards on the table
• put down roots
• put down to experience
• put feet up
• put finger on
• put finger on something
• put flesh on
• put flesh on something
• put flesh on the bones of
• put flesh on the bones of something
• put foot down
• put foot in it
• put foot to the floor
• put forth
• put forth something
• put forward
• put forward something