Possible Clues:

• Bother sister over savings scheme before church
• Problem is masked in subtlety
• One’s going into fine distinction — bother!
• Something obnoxious exists to split subtle difference
• Annoying thing is involved in subtle difference
• Fine distinction going round is something that annoys us
• Mild distinction about island plague
• Irritant
• Trouble is found in small change perhaps
• The pain is in the subtle distinction