Possible Clues:

• Lake invading cave in a swinging Spanish port
• Spanish Med city
• Wandering clean through by way of Mediterranean area
• Mediterranean port, Nice, unfortunately swamped by molten lava
• Spies following lead casing the French port
• Mediterranean city's greeting to departing North American spies
• Evil can spread round a Spanish city
• During holiday, Leonard and I head for ancient Spanish city
• Winding canal I've found in foreign city
• Spain's third largest city