Mr. Clark is a fundamentally good dude stuck in a tough spot. A lifelong factory worker, he's laid off halfway through the novel, which leaves him unemployed for the first time in his life.
This has a profound effect on him. Not only is he not making money, which is bad for obvious reasons, but he's also lost his sense of purpose. He's no longer able to provide for his family. To make the situation worse, "prospects for a fifty-five-year-old man who had only ever held one job" aren't exactly good (14.11).
Amazingly, however, Mr. Clark scores a gig working as the groundskeeper at Stortford Castle. Sweet deal. Of course, he only lands the job because Will blackmails his dad, who own the castle, but hey—whatever works. Plus, Mr. Clark is an undeniably hard worker and good guy, so we're sure he'll do an exemplary job in the position.
Either way, things are looking up for our favorite father by the end of Me Before You. Good for him.