Italian town, unaltered over centuries, at last beginning to industrialise (6)
I believe the answer is:
assisi
'italian town' is the definition.
(I've seen this before)
'unaltered over centuries at last beginning to industrialise' is the wordplay.
'unaltered' becomes 'asis' (I've seen this in other clues).
'over' indicates putting letters inside.
'at last' says to take the final letters.
'beginning to' indicates taking the first letters.
The last letter of 'centuries' is 's'.
The initial letter of 'industrialise' is 'i'.
'asis' enclosing 's' is 'assis'.
'assis'+'i'='ASSISI'
(Other definitions for assisi that I've seen before include "Homeplace of St Francis" , "Italian town, birthplace of St Francis" , "saint from here" , "St Francis was born in this Italian town" , "town, in Italy" .)