1 general:: Be close to death or in terrible condition, as in Jane looks as though she has one foot in the grave. This picturesque hyperbolic phrase was first recorded in 1566.
American Heritage Idioms
2 general:: Phrase(s): have one foot in the grave Fig. to be almost dead. • I was so sick, I felt as if I had one foot in the grave. • Poor old Uncle Herman has one foot in the grave.
McGrawhill's American Idioms And Phrasal Verbs