Possible Clues:

• Prime minister’s dismal horse
• Gloomy, elegy writer, from what we hear
• "Fifty Shades of ___"
• Neither black nor white, in Britain
• Anne Brontë's Agnes?
• Cases of Gewürztraminer, exceptionally pale
• Horse in stayer galloping around
• London fog descriptor
• 'Fifty Shades of —'
• Overcast, in Britain