Related Clues:

• That's a bit thick for the lairs over the East
• None too quick on the uptake
• Like depleted uranium
• Packed with ideas, as an essay
• Practically impenetrable
• In need of a tow
• The street heard, you see, Kay was baffled
• Hard to get through
• Thick, like fog
• Bogged down a bit in Germany
• Thick wooded valley around the point
• Several rooms with one key? Stupid!
• Not very bright — needs to be properly organised
• Dim woman lacks ego
• Needs to be close