Related Clues:

• Undivided, as attention
• 'While you're ___ ...'
• Trying hard
• Lost in a good book, say
• Engaged, and then some
• Doing something
• Toiling hard
• "Look ___ this way ..."
• Not at all distracted
• Toiling or bickering
• All eyes and ears
• Fully engrossed
• Busy working
• Riveted with attention
• Glued to the tube, say