Going to a restaurant, or dine at home, with painful disease (6,3)
I believe the answer is:
eating out
'going to a restaurant' is the definition.
'dine at home with painful disease' is the wordplay.
'dine at home' becomes 'eatin' (I've seen this before).
'with' means one lot of letters go next to another.
'painful disease' becomes 'gout'.
'eatin'+'gout'='EATING OUT'
'or' acts as a link.
(Other definitions for eating out that I've seen before include "Forgoing home cooking" , "Dining in a restaurant" , "Patronising a restaurant" .)