Old Roman general from Riga mixed drink

• General passages written up inspired by Indian city?
• See 12 Across
• Roman has drink with Greek in perfect setting
• A king has one coal supply in 19
• Roman general who was governor of Britain and extended Roman rule north to the Firth of Forth (37-93)

Wikipedia Word definitions in Wikipedia
Agricola ( fl . 466–485) was a son of the Western Roman Emperor Avitus .