Related Clues:

• Hard to see through
• Far from 22-Down
• Overgrown
• Hard to see through, as fog
• A little on the slow side
• Not sparse
• Not Mensa material
• Compacted
• Not the sharpest pencil in the box
• Not very sharp
• A few bricks shy of a load
• Highly concentrated
• Tough to get through to
• Hard to get through to
• Like a thicket