Possible Clues:

• Tree with less on top, pollarded
• Tree covering more than half of Channel Island
• Tree's more exposed with top removed
• Civic dignitary would plant this tree on isle
• Forward movement
• Jim, Scot who won a Commonwealth Games marathon gold medal
• May trees get shot for the British army there?
• Native tree
• A tree for Adler
• Cut top off less leafy tree