Possible Clues:

• Indulgent, lax
• Let it be about 15 across, but not strictly speaking
• Willing to let things slide
• Light inside regularly seen in some of springtime
• Merciful or easygoing
• Mild European imprisoned by famous Communist despot, ultimately
• Strictly speaking, it's not let around nine
• Allow about nine out, being merciful
• 'Indulgent, easy (7)'
• Mild man and I meet at hospital department