Possible Clues:

• How a box may be set
• Working to finish without pause or interruption
• Vertically
• For hours __ (interminably)
• Upright, and what's been removed to form this puzzle's theme answers
• Set upright
• Upright individual's state
• For weeks __ (continuously)
• Like hair after being rubbed with a balloon, maybe
• How unruly hair may stand