Archdeacon coming to Italian city — good undertaking (9)
I believe the answer is:
venturing
'undertaking' is the definition.
(to venture is to undertake or commit something)
'archdeacon coming to italian city good' is the wordplay.
'archdeacon' becomes 'ven' (abbreviation for The Venerable).
'coming to' says to put letters next to each other.
'italian city' becomes 'turin' (Turin is a city in Italy).
'good' becomes 'g' (abbreviation).
'ven'+'turin'+'g'='VENTURING'
(Other definitions for venturing that I've seen before include "Taking a risk" , "Daring" .)