Possible Clues:

• Lose memory of
• Smith might not have it in mind to be there before tea
• Neglect (to do)
• You won't mind if you find Smith there over tea
• It may slip your mind that Smith will be there before tea
• Out of your mind for 20 down
• Not remember
• You'd be out of you rmind to expect to find Smith there before tea
• Be unable to recall
• Totally blank on