Redressing mere indisposition with one foot in the grave (9)
I believe the answer is:
remedying
'redressing' is the definition.
Although both the answer and definition are present participle verbs, I don't understand how one could define the other.
'mere indisposition with one foot in the grave' is the wordplay.
I cannot really see how this works, but
an anagram of 'mere' is 'reme' which is within the answer.
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for remedying that I've seen before include "Putting right (an undesirable situation)" , "sorting out" .)