Two of the unclued entries combine to form a name (three words) responsible for the other unclued entries (one of three words, two of two words, and two of which combine to form a two-word name).

Across

11    Custom I outlaw, hiding books for islander (7)

12    They must cool down the crowd (4)

14    Cast spell over snake in Paradise Lost? (6)

15    Natal piece, that is ejected somehow (8)

17    Fruit is cut back (5)

19    Things a man hates terribly (9)

21    The wrong tribe ultimately settled in Nevada desert (5)

23    I was a boss and had nothing to do (5)

25    Songbird’s attempt to conceal guano...