Another option could be 'parable'. Parables are short stories that convey a religious or moral lesson. While they are generally short, some parables can be more elaborate and thus considered a 'long short story' in relation to the crossword clue. Parables are found in many religious and cultural traditions, like in the Bible for example, and their length and complexity can differ.
One answer could be 'yarn'. 'Yarn' can mean a story, and it can be used to describe a long short story in a more informal way. For example, someone might say 'He spun a long yarn about his adventures.', which implies a somewhat long story that still has the essence of a short story.
A 'tale' could be an answer. Tales can range in length from very short to relatively long. They are a form of short story, and if it's a more extended tale, it can be seen as a 'long short story' which would work for the crossword clue.
Suppose the crossword clue in the 'Enigmatic Puzzle' story is 'A building where people pray'. There are many possible answers such as 'church', 'mosque' or 'temple'. It depends on the context of the crossword. If it's a crossword with a more Western - centric theme, 'church' might be more likely. If it's more general or global, all three could be valid answers. You need to look at other intersecting words in the crossword to be more certain.
I'm not sure what the specific crossword clue is in this 'Mysterious Word' story. But generally, you should look for hints like the length of the word, whether it's a noun, verb etc. If it's a clue related to a specific theme, for example, if it's a travel - themed crossword and the clue is 'A place with a lot of sand by the sea', the answer could be 'beach'.
One of the most famous Nabokov novels is 'Lolita'. It's a controversial yet highly regarded work that tells the story of Humbert Humbert's obsession with a young girl. The novel is known for its complex narrative structure and Nabokov's masterful use of language.