Refine, as a skill

HONE

Think of what you might do to a knife blade or a craft to make it sharper or more precise over time.

"Refine, as a skill" points to "HONE" because "hone" literally means to sharpen or perfect something over time, like a skill or ability. The word is often used in phrases like "hone your craft," making it a natural fit for the idea of gradual improvement. There’s no hidden wordplay here—it’s a straightforward definition clue.