Definitions for one up
Random House Webster's College Dictionary
having gained an advantage, esp. over a rival.
Origin of one up:
to gain an advantage over; be a move, step, etc., ahead of:
to one-up the competition.
Category: Common Vocabulary
Origin of one-up:
An additional life or object that gives the player an extra chance to play.
To outdo, to do something slightly better than a competitor's prior effort.