Never smoked but still sick (7)
I believe the answer is:
uncured
'still sick' is the definition.
Both the answer and definition are adjectives. Perhaps you can see an association between them that I don't see?
'never smoked' is the wordplay.
'never' becomes 'un' (I can't explain this - if you can you should give a lot more credence to this answer).
'smoked' becomes 'cured' (I've seen this before).
'un'+'cured'='UNCURED'
'but' acts as a link.
(Other definitions for uncured that I've seen before include "Still ill; not smoked, salted or dried" , "Not preserved by salting, drying or smoking" .)