Combine 2 cups tomato juice, onion, celery, brown sugar, salt, cloves, bay leaves, and garlic in a heavy saucepan.
Bring to a boil; reduce heat and simmer, uncovered, 5 minutes.
Strain mixture; discard vegetables and spices.
Soften gelatin in 1 1/4 cups tomato juice; add to strained hot juice mixture, stirring until gelatin dissolves.
Stir in lemon juice, Worcestershire sauce, horseradish, and remaining 3/4 cup tomato juice; chill until consistency of unbeaten egg white.
Fold green pepper into gelatin mixture.
Pour mixture into a lightly oiled 4-cup mold; chill until firm.