Clues were as follows:
16: Cruel time for lake isle without leader to start with (5)
april = [c]apri+l. "April is the cruellest month" is the first line of Eliot's
The Waste Land.
3: Part of month possible for king (6)
oberon = [oct]ober+on. Oberon is king of the fairies in mediaeval European literary tradition, see i.e.
A Midsummer Night's Dream.