If someone is waiting in the wings, they are waiting for an opportunity to take action, especially to replace someone else in their job or position.
Ready or prepared to do something, especially to take over someone else's job .
Atul was waiting in the wings, hoping that the captain of the team would drop out and he would get that place on the team.
There are many young Engineers waiting in the wings, ready to show their talent.
The Minister retires next year and Mr.Kumar is just waiting in the wings.