Possible Clues:

• "Oh, when will they __ learn?": Seeger lyric
• 'Don't ___ give up!'
• With 43-Down, fairy-tale ending
• For or what ending
• Word following who, what, when or how
• First Lady meeting resistance at all times
• 'If I ___ ...'
• Nonstop
• Lived happily ___ after
• "Thanks ___ so much"