I know this is a circus theme, but is it a 'formal' banquet? What I mean, is it an event that is using some circus thematics (like balloons and popcorn on the tables) or are you going for circus fare?
Here's what I was thinking...
> Little, battered corn dogs as butlered appetizers with a maple dipping sauce
> Individual pizzas
> "Adult" Snow Cones - shaved ice with liquors (like Midori,
Chambord, etc) as the coloring
> Smoked turkey drumsticks
> Caramel corn, made on site
> Warm Cashew brittle
> Stuffed funnel cakes, with cinnamon apples and whipped cream
> 'Slider' hamburgers... 2 oz patties on little square rolls
> Hand cut french fries
The dinner is for an elderly singles group. It will be a very basic meal. 2 entrees, 1 toss, 2 side salads, a potato, veggie,and dessert. They want the menu to fit the theme. All I can come up with are a cotton candy fruit whip and a caramel apple cake.
I think Jim's suggestions are fantastic and I would pitch that meal to the group. Maybe they'll go for it. If not, maybe the best you can do is serve food that has a little pizzazz and dress it up with circus-theme table settings and garnishes. How about Chicken Kiev for one of the entrees and popcorn shrimp for the other? You could serve with roasted blue potatoes or handmade blue potato chips and the vegetable could be a colorful slaw with red and green cabbage and carrots.
Dessert, clearly, should be something you can set aflame. In fact, just about anything you set on fire probably will do the trick. You could even do some sort of flaming Kabob for an entree and either make the popcorn shrimp and appetizer or just out a mess of popcorn shrimp on each table, family style.
Pump in some circus music. Pick up a CD of Fellini movie themes by Nino Rota.