Special instructions for this puzzle - if I read them correctly, the clue given might not correspond to the letters shown...
Thirteen clues consist of wordplay alone and share the same
missing thematic definition. However, the wordplay for the first
of these solutions has slipped and appears as the clue for the
second, that for the second to the clue for the third and so on.
(The wordplay for the 13th solution is the clue for the first.)
With 13 other clues the definition of each solution contains a
misprint. Corrections to these misprints in clue order spell out
the reason for the 13 thematic shifts.