### Clue: Economist worries unduly about Hebridean island where the rich live (12,3)
### Answer: MILLIONAIRES ROW 
 ### Explanation: Definition: where the rich live
An envelope ('about') of IONA ('Hebridean island') in MILL (James or his son John Stuart, 'economist') plus IRESROW, an anagram ('unduly') of 'worries'.