It depends on what pattern you’re using, though the most common is the 6-4-1-1 pattern so I’ll assume you’re using that.
once you reach Elliot’s cabin (or any of the tiles that you can’t till), you can either hoe any tile as a replacement (not getting clay but still advancing the pattern), or use replacement tiles (hopping onto another “thread” of clay).
the easiest replacement tiles are 3 left/2 up and 3 right/2 down (might be 2 left/3 down I’ve honestly forgotten so test it out, regardless it’s an ‘L’ shape). These tiles will drop a piece of clay, and since any tilled tile advances the pattern, you’ll just resume back to the tile after the one that was blocked.
of course, you’ll eventually reach the water and can’t productively proceed with the same pattern, in which case you’ll need to find a replacement much farther back and both hoe and pickaxe (to undo what you’ve already hoed), or use a different location entirely such as outside robins (good because she buys the clay)
