Possible Clues:

• One has experience in getting the tree into the van
• Of old, got a beastly practice near there
• Bonus Army member
• Is the beastly doctor getting near to confused and old
• Never at 9 across and never 9 across
• ... experienced without 50 relevant changes
• One of great experience
• Old soldier put off leading out in front
• Not an amateur
• Experienced doctor managed to overcome disease at last