master_list = sc.parallelize([["A",1,2,3],["B",4,5,6],["C",7,8,9]])

master_list.flatMap(lambda x: [[x[0], x[i]] for i in range(1, len(x))])

['A', 1]
['A', 2]
['A', 3]
['B', 4]
['B', 5]
['B', 6]
['C', 7]
['C', 8]
['C', 9]