Upset Catholic, Italian, I initially considered a fault-finder (6)
I believe the answer is:
critic
'a fault-finder' is the definition.
(I've seen this before)
'upset catholic italian i initially considered' is the wordplay.
'upset' says the letters should be written backwards.
'catholic' becomes 'rc' (I've seen this in other clues).
'italian' becomes 'it'.
'initially' says to take the initial letters.
The initial letter of 'considered' is 'c'.
'rc' backwards is 'cr'.
'cr'+'it'+'i'+'c'='CRITIC'
(Other definitions for critic that I've seen before include "Evaluator, reviewer" , "Supposedly expert judge of films, music etc" , "Commentator, pundit" , "Reviewer of plays, films etc" , "One analyses and interprets works of art" .)