to do something when someone else cannot or will not do it.
With our best player injured, other players picked up the slack.Who will take up the slack when our grant money runs out?
pick up the slack
To do an extra amount of work that someone else is unable or unwilling to do. I'm going to need you to pick up the slack around the house when the baby arrives, because I'm going to literally have my hands full.The fourth member of our team has been totally unreliable, so the rest of us have had to pick up the slack.