Involved tea in complaint at restaurant (6,3)
I believe the answer is:
eating out
'involved tea in complaint at restaurant' is the definition.
I can't tell whether this definition defines the answer.
'involved tea in complaint' is the wordplay.
'involved' is an anagram indicator (involved can mean confusing or complex).
'complaint' becomes 'gout' (gout is a kind of disease).
'tea' anagrammed gives 'eat'.
'eat'+'in'+'gout'='EATING OUT'
Can you help me to learn more?
(Other definitions for eating out that I've seen before include "Dining in a restaurant" , "Forgoing home cooking" , "Patronising a restaurant" .)