Italian tourist destination in Colosseum ultimately saved by the last John Paul? (7)
I believe the answer is:
pompeii
'italian tourist destination' is the definition.
(ruins of Pompeii in Italy)
'colosseum ultimately saved by the last john paul?' is the wordplay.
'ultimately' indicates one should take the final letters.
'saved' indicates putting letters inside (save can mean to keep hold of).
'by' becomes 'pope' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'the last john paul?' becomes 'II' (John Paul II, last of two popes called John Paul).
The last letter of 'colosseum' is 'm'.
'm' placed into 'pope' is 'pompe'.
'pompe'+'ii'='POMPEII'
'in' acts as a link.
(Other definitions for pompeii that I've seen before include "Town buried by Vesuvius 1st century a.d." , "Roman town buried by Vesuvius" , "Vesuvius-buried town" , "Roman city destroyed in 79AD" , "Ancient city buried when Vesuvius erupted" .)