Clay courts are messy, dusty, and can be quite fussy.
A couple of things that can happen to a hard court, leaves piling up or bird droppings, can be washed away with a hose.
The red clay courts of Roland Garros, the very thing that makes the French Open so special, require a lot of TLC to stay in good repair. The courts are resurfaced, between every set, by the grounds crew. It's an old school approach, as they drag what looks like a piece of an old net, nailed to a board, that's connected to a rope, to even out the drag marks and small divots in the terre batue.
The white lines, which are permanently affixed into the the dirt, are brushed off with a broom. The final step is a light watering down of the dirt, with a fine spray delivered through a small firehose. The water is absorbed quickly, thanks to the thirsty dirt, and play soon resumes. It's a deliberate process, but one that leaves the clay court in pristine condition, much like a Zamboni does for an ice rink.