Possible Clues:

• How sickening for a pair of fruit not to sound like a pear
• Be with the Irish king, twice, and get the disease
• It's caused by thiamine deficiency
• Tropical disease affecting nerves
• Exist with ridicule and anger about disease
• Ale one smuggles to guy with sickness
• Double fruit, we hear, for vitamin deficiency problem
• Sounds like blackcurrant and sloe together perhaps can produce sickness
• Disease of fruit, we hear, being duplicated
• Sources of vitamin administered orally for tropical disease