"a major ask" is correct and usable in written English.
You can use it to refer to a large or demanding request, or a difficult task. Example: She had a major ask of her co-workers - to finish the project in three days.
"Does Lee Westwood need to reach 40, the Dawning of the Age of the Mature Man, in order to win a major?" asks Adam Hirst.
College admissions officers cringe at questions like, "Do you have a psychology major?" Ask thoughtful questions about research opportunities, career paths for graduates, available internships and tough questions about social life and campus culture.
A Hofstra student interviewed Tamara for a class assignment, and a senior communications major asked to do his final project on the twins.
Strange as it may sound, but there is a danger with holding a large lead going into the final round of a major, just ask Greg Norman and Rory McIlroy.
Sometimes that involves a recording that is rights-controlled by a major (just ask Cyril Hahn).
If the fare is to a major airport, ask if there's a flat rate vs. a metered rate.
When a major newspaper asked him to write an op-ed about the Weiner scandal, he declined.
"How often, if ever, has a third-choice keeper been used in a major tournament?" asks Ross Knight.
Have BSkyB, as a major shareholder, asked for meeting with the board/independent directors regarding either strategy or the chief executive role?
In fact, according to one longtime resident and local broker in this tight-knit community in northern Burlington County about 65 miles from New York, that is exactly what happened a few years back, when a major developer asked a group of real estate agents from several communities for their thoughts about the planning of the much-talked-about Town Center project in nearby Washington Township.
