Dumplings and grumblings don't rhyme. No wonder the SPELLing spell didn't work for you.

Weasel back to horse:
First,
Drop L; Then drop E so it
Changes WEASE to WEAS
Change WEAS to WOES
Add back E
Change WOESE to WORSE
Change WORSE to HORSE.

Unless, of course, you want a horse of a different colr. That is covered in the Advanced Course.