Mix yeast, water, and sugar together in a small bowl.
Set bowl aside in a warm, draft-free location, 10 to 15 minutes, until contents bubble, as proof the yeast is active.
If it does not bubble, discard the mixture and start again with fresh yeast.
Sift flour and salt into a medium-sized bowl.
Create a well in the center.
Pour in the yeast mixture, milk, and egg.
Add the softened butter; whip or beat all until well combined.
(Mixture will be loose at this point.) Cover the bowl with a tea towel and let rise in a warm, draft-free location until double in bulk, about 1 hour.
When mixture has risen, brush the bottom of a heavy skillet with some of the clarified butter.
Place pan over medium heat.
Arrange buttered crumpet rings in the pan, filling each ring 1/3 of the way up with batter.
(If you have no crumpet rings, you can use cans 1 1/2 inches high by 3 inches wide, cutting off the tops and bottoms of the cans before using.
A 7-ounce tuna fish can works perfectly.