Possible Clues:

• Nickname for Mendelssohn's Third Symphony
• Glaswegian, possibly, rather like Sir Walter?
• Such people prefer it to Scotch for themselves
• Liable to become intoxicated about leading edge in computers, like Macs
• Small crib with this problem for one lot of the Celts
• From Aberdeen?
• Those from the granite city presumably producing alternative to schist
• Nationality of extreme independent socialists' leader visiting school
• Caledonian school accepting books it's condemned!
• Like William Wallace's outdated tax, this is complicated