Replace on the mound

RELIEVE

Think of what a baseball manager does when the starting pitcher is struggling mid-game. The word also means to ease a burden.

"Replace on the mound" is a baseball reference where "mound" means the pitcher's mound. The word "replace" hints at swapping out the starting pitcher, which is the role of a relief pitcher—shortened to "relieve" in crosswords. The clue plays on the double meaning of "relieve" as both taking over for someone and providing relief.