Possible Clues:

• Drink up the water to make 3 down sick
• The cattle out in the rain swallowing rum are infectious
• Old name for cattle or sheep diseases, sometimes used to describe a biblical plague of Egypt
• One gets beastly sick of spirits back there with water
• To get the rum up with water is enough to make one beastly seedy
• Return of the odd wet weather causing cattle plague
• The 11 across of returning 27 across before it's wet
• Cattle-plague
• The end of 13 across gets wet to make the herd sick
• Endless gloom and wet weather brings animal disease