Old surgeon gives CH, from the old word chirurgeon (cf the French chirurgien) - I've seen that used before - not sure how slightly mad gives FIE - I can think of a few equally weak possibilities but nothing solid. Sorry can't help with the other - BEGNAW will fit but not sure why.
Thanks people. I should have known about the surgeon thing as, as when I was an apprentice (40-odd years ago) my journeyman always used to boast about his son who was training to be a doctor at Edinburgh University and part of his qualification was Ch. B. (Bachelor of Chirurgery) A Guid New Year tae ye when it arrives. Lang may yer lum reek.