Fun with "FEN"

Marketed under popular brands like 'Cashyo', 'Reals' , and 'Big Boss' the product is registered under the GI (Geographical Identification) name "****" and is described as a colourless clear liquid when matured in wooden barrels getting golden brown tint. The word "****" which also is the name of a district located in Bangladesh,  is derived as such because when the liquor is shaken in a bottle or poured in a glass some froth is formed which in the local language is known as "FEN”.

 What beverage is being described here??