Possible Clues:

• Senile one
• Senile sort
• Feebleminded person
• Feeble fellow
• 'Not Crosaire yet, please God, one has to do this up, drat it (6)'
• One showing weakness in old age
• Senior senior
• When one begins to get dotty, get a doctor up
• Cheat mostly slow old fool
• Old man's curse, reeling after swindle