verb

temporarily act or speak on behalf of someone else.

the post-holder is required to deputize for the manager in their absence

stand in for,sit in for,fill in for,cover for,substitute for,replace,take the place of,understudy,be a locum for,relieve,take over from,hold the fort,step into the breach,act for,act on behalf of,speak on behalf of,represent,sub for,pinch-hit for