Anger is heard in this old region (4)
I believe the answer is:
gaul
'this old region' is the definition.
(historical region including modern-day France)
'anger is heard' is the wordplay.
'anger' becomes 'gall' (galling is a kind of angering).
'is heard' shows a homophone (sound like).
'gall' sounds like 'GAUL'.
'in' acts as a link.
(Other definitions for gaul that I've seen before include "Ancient region of France/Belgium in Caesar's time" , "Ancient Western European" , "Asterix, for example" , "old country" , "Ancient area of western Europe" .)