7 Across: Nothing changes egg producers (7 letters). The first letter is an "o." Stay tuned!
Cryptic crossword clues are simultaneously definitions and other types of word puzzles: hidden words, anagrams, reversed words, double meanings, and more! But there's a trick: the puzzle solver doesn't know which type of word play she has encountered until she also knows which word might point to the definition. For instance, "nothing changes egg producers" might mean that a word meaning "nothing" is an anagram of the letters in "egg producers" or vice versa. It could also mean that a word meaning "nothing changes" also means "egg producers," or that a word meaning "nothing" is inserted into "egg" to form a 7-letter word meaning "producers." etc.
Also, each clue is itself a short (and quasi-logical) sentence or fragment that has nothing to do with the answer itself. So the reader must simultaneously perform several operations on the clue: reading the sentence as a whole and for its possible combinations of constituents, reading each word (and constituent) to find a)its synonyms, b)possible operations in the clue it might indicate (ex: "changes" might mean that a word's letters are scrambled), c)combinations of letters in it that might form other words, d)its homophones, and more...
But none of these operations alone is enough to guarantee a solution to the puzzle. The reader, as they read, must perform the above operations to generate possible solutions, and simultaneously cross-check them with the other operations occuring on the other words in the clue and the possible types of operations being performed by the clue writer, etc. whew! complicated run on sentences describing mental processes!
But a process like this one seems to better simulate what goes on in language processing than the model which seeks to separate semantics from syntax from phonology from morphology. As in the recently-posted recipe, which i still urge you to try, in real language processing environments, we can distinguish between "apple" and "an apple" without the presence of the article on the basis of context. we can use homophones to read through typos and misspellings (i typed "nugmeg" for "nutmeg," but the reader could still understand it), we can manipulate mulitple meanings of the same word or phrase to understand puns, irony, idiom, and metaphor ("keep an eye on crust brownness"--eww!), and can easily judge the meanings of technically ambiguous sentences and references on the basis of context ("press all into pie dish with your fingers" might sound like an ancient proverb, but "all" means all the dough, not all of creation).
And, to press all into pie dish with my fingers: we achieve understanding about the syntax of the sentence and the meanings of the indivdual words at the same time. Neither recipes nor cryptic crossword clues can be understood by sifting each word separately and then mixing them together.
Answer: OVARIES, (it's a synonym for "egg producers," and it's also 0[meaning "nothing"] + VARIES [meaning changes])