Clamato, a product of Mott's, is what the company calls a 'Tomato Cocktail'. Cocktail? There's no roosters in there! What it does have is Tomato Juice (duh), Celery Juice, Onion and, you guessed it, CLAM BROTH.
In its literature, the company makes a big deal that the amount of clam broth is less than 1/100 of total volume, and that the .1% is just there to give it a zesty zing.
Some people really like it and many swear ( and fall over ) by Clamato Bloody Marys. I, however, think it's rather vile. Clamato is a true child of the 1970's if there ever was one.