Possible Clues:

• It's the 'D' in a presidential monogram
• F.D.R.'s middle name
• Old White House middle name
• Historic White House middle name
• Franklin -- Roosevelt, 32nd president of the USA
• The "D" of FDR
• White House middle name
• Roosevelt preceder
• '30s White House mom
• Name of a family from which Franklin Roosevelt was descended