Not speaking, not at first, having called back atmosphere in Italian region (6)
I believe the answer is:
umbria
'italian region' is the definition.
(Umbria is an example)
'not speaking not at first having called back atmosphere' is the wordplay.
'not speaking' becomes 'dumb'.
'not at first' means to remove the first letter.
'having' means one lot of letters go next to another.
'called back' shows that the letters should be reversed in order.
'atmosphere' becomes 'air' (synonyms).
'air' back-to-front is 'ria'.
'dumb' with its first letter taken off is 'umb'.
'umb'+'ria'='UMBRIA'
'in' acts as a link.
(Other definitions for umbria that I've seen before include "hilly area of Italy" , "part of Italy" , "Mountainous region in central Italy" , "Italian region" , "in the Tiber region" .)