Possible Clues:

• Solemn, not inclined to flippancy
• One buried inside watery grave
• Notable person from Belgrade cut debts?
• Concerned with component of blood containing iodine — that’s worrying
• Important — grave
• Earnest South American touring eastern port
• Stern
• Grave issue — or resolved
• Considering marriage
• Earnest and oddly sweary notes from short people