Combine 4 cups water and sugar in a heavy saucepan; bring to a boil. Cook until sugar dissolves; remove from heat. Add cloves, tea bags, and cinnamon; steep 5 minutes. Strain mixture through a sieve into a pitcher; discard solids. Add remaining 2 cups water, juice, and lemonade concentrate; stir well. Chill. Serve over ice, and garnish with lemon slices, if desired.