Possible Clues:

• Prime minister engaged in battle eventually
• Clement -, UK PM
• Leader once in a race over London green
• Clement -, PM nineteen forty five - fifty one
• About whom Churchill purportedly said 'A modest man who has much to be modest about'
• Clement . . . . . . was British PM post WW2
• Prime minister, 1945-51
• Prime minister nineteen forty five to fifty one
• Former British PM
• PM on the sheltered side keeping dry