Place cheese and cornstarch in a bowl and toss to coat evenly. Set aside.
Rub the inside of the fondue pot with the garlic clove. Discard garlic.
Add beer to a medium saucepan. Cook over medium heat until liquid is simmering. Gradually add handfuls of cheese to the saucepan, stirring until each handful is melted before adding more. Remove from heat and stir in mustard, ground red pepper and Worcestershire sauce once all cheese is melted.
Pour cheese mixture into prepared fondue pot and keep warm.