Related Clues:

• Overgrown
• Hard to see through, as fog
• White-knuckle
• A little on the slow side
• Part of the answer to 36-Down
• Not sparse
• Not Mensa material
• Compacted
• Like thickets
• Not the sharpest pencil in the box
• Not very sharp
• A few bricks shy of a load
• Tough to get through to
• Hard to get through to
• Strongly felt