The answers to the following clues will have something in common.

1. Marines
2. Rabbits
3. Ancient Trade Route
4. Celebrated rock and roll footwear
5. Prehistoric giant
6. Winter nightware

Answers:

1. Leathernecks
2. Cottontails
3. Silk Road
4. Blue Suede Shoes
5. Wooly Mammoth
6. Flannel pajamas