The Colliseum is in one of those areas where major roads are barriers to foot traffic and to development of small shops and restaurants.
The closest restaurant would be in the hotel just up the hill. The next closest would be Ruth's Cris, overlooking the river and then Calhoun's on the river.
Take the south Knoxville connector to Chapman Hwy to Ye Olde Steak House (open only for dinner), it's Knoxville's long standing best steak house and if you love potatoes, you need to try their woodshed potatoes which are a roasted delight with onions and pepper.
Many restaurants on Market Square are also good, but smaller and maybe more interesting. Lots have been discussed here.
Ye Olde Steak House
6838 Chapman Hwy, Knoxville, TN 37920
Bistro at the Bijou
Downtown Grill and Brewery
Barley's Taproom and Pizzeria
The Crown and Goose
Boyd's Jig and Reel