bank undercutting
Here is a good example of an undercut bank. Current, wakes, runoff, and other factors contribute to the creation of undercuts. Fish like to hide in the undercuts, especially in shallow rivers. In this photo there are portions of the bank that hang down into the water creating almost a cave type environment. Fish hiding in these undercuts can be easily spooked so a silent approach is usually a good idea. Structure Library - Undercut Bank
Whenever possible, try to cast beyond where you think a fish might be and bring your lure past the fish in as natural a fashion as possible. If casting at the undercut, use lures that wont make a large splash. Plastic lizards, small tubes, and similar lures with a minimum of weight landed on the bank and allowed to crawl into the water work very well.