What many, with age, suffer from in winter (8)

'what many' is the definition.
I can't tell whether this definition defines the answer.

'age suffer from in winter' is the wordplay.
I cannot really understand how this works, but
'age' could be 'oldness' (oldness is a kind of age) and 'oldness' is found in the answer.
A single letter 'c' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

'with' is the link.

Can you help me to learn more?