In a game, "he was sent to level-grind" would work. Provided you make levels that you actually have to grind -- 5e has absurdly easy leveling when you look at realism considerations -- and you work in how many clerics there would be adventuring because of it -- even if only one in a hundred clerics makes it to second level, the benefits would be enormous.

In a story, less so unless you play up the dynamics of it.