To take the place of
act for, do the work of, replace, supplant, displace, supercede, take another's place, double for, answer for, make way for, count for, serve in one's stead, pass for, go for, go as, step up, fill another's position, take over another's duties, fill in for, pinch-hit for*, take the rap for*, sub for*, spell*, go to bat for*, ring in*, front for*, fill someone's shoes*.