No-one else has asked this so I feel a bit foolish. I've finished the crossword (thanks, Brendan) and have faithfully listed the 'features' from half the clues and the additional letters from the others. But I can't find any rearrangement of the latter that makes words, let alone that relates to the features. I can extract one word that obviously does, but that leaves me with a heap of letters that don't rearrange into anything. Have others solved this more satisfactorily?