Damned well after illness, containing second (6)
I believe the answer is:
cursed
'damned' is the definition.
('curse' can be a synonym of 'damn')
'well after illness containing second' is the wordplay.
'well after illness' becomes 'cured'.
'containing' is an insertion indicator.
'second' becomes 's' (common abbreviation**).
'cured' placed around 's' is 'CURSED'.
(Other definitions for cursed that I've seen before include "Blasphemed" , "Damned" , "Hateful" , "Anathematised" , "Uttered imprecation, swore" .)