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

1. Dangerous course
2. Hardly an elite eatery
3. Shrewdie
4. Driving hazard after a light rain
5. 6:00 a.m. in Brooklynese

Answers:

1. Slippery slope
2. Greasy spoon
3. Smooth operator
4. Slick roads
5. Oily in the morning

Credit: 
Kurt Mengel and Jan-Michele Gianette