MELT butter in medium saucepan over medium heat. Add potato, carrot, celery and onion. Cook, stirring frequently, for 7 to 8 minutes or until potato is tender.
COMBINE evaporated milk and flour in small bowl until blended; add to vegetable mixture. Stir in clams and juice, salt, Worcestershire sauce and pepper. Reduce heat to medium-low; cook, stirring frequently, for 15 to 20 minutes or until creamy and slightly thick.