Barium processed in Italian region (6)
I believe the answer is:
umbria
'italian region' is the definition.
(Umbria is an example)
'barium processed' is the wordplay.
'processed' is an anagram indicator.
'barium' anagrammed gives 'UMBRIA'.
'in' is the link.
(Other definitions for umbria that I've seen before include "Italian region" , "hilly area of Italy" , "in the Tiber region" , "Mountainous region in central Italy" , "part of Italy" .)