Possible Clues:

• Not at all bored
• King inclined to be enthralled
• Undivided, as attention
• Enraptured, entranced
• Like one diffusing a bomb
• Utterly absorbed in something, say
• 'Transported, entranced (4)'
• Not at all distracted
• Fully engaged, as is right and proper
• Lost in a good book, say