Related Clues:

• Bottom of cooling tower is dark
• Good to take on threatening shape in darkness
• Dark brush changing hands
• Grand tower in partial darkness
• Air of despair
• Opposite of transparency
• Apt rhyme for "doom"
• Light of dusk?
• Work with a business community — there's a lack of transparency
• Depression of key on weaving machine
• Low spirits start to get lower?
• Doom and ___