The phrase "a difficult reservation" is correct and usable in written English.
It can be used when referring to a reservation that is challenging to secure or arrange, such as for a restaurant, hotel, or event.
Example: "I tried to book a table at the popular restaurant, but it turned out to be a difficult reservation to make."
Alternatives: "a challenging booking" or "a tough reservation".
If you know your schedule, it's worth booking from the United States; Gordon Ramsay, especially, can be a difficult reservation.
On any given day, he can arrange a private cruise on the Seine or land a difficult reservation at a three-star Michelin restaurant.
The Polo Bar, Ralph Lauren's new restaurant, off Fifth Avenue, is a difficult reservation to secure, but, on a week night in late March, Bratton and his wife, Rikki Klieman, a legal analyst for CBS News and a former criminal-defense attorney, were sitting in a choice banquette along the wall.
But it is not just the food that makes this place a difficult reservation in San Francisco; the staff is cheerful, helpful and efficient.
So, last April, a question came in: "A statement that Doug made in a letter today was 'Most of our reliability issues were related to a difficult reservations system migration.
That was the most difficult reservation to obtain.
Ah, one of the notoriously difficult reservations to get and one of the most magical places where you can eat dinner in this city.
It was a difficult program, and one may say, with some reservations, that on his own terms Rosenberg makes it work.
Harding is a difficult, occasionally obnoxious person, for whom we end up rooting without reservation.
Even his birth had been a difficult one, and it was reported — though here the author of "The History" voices some reservation — that the newborn had teeth.
Despite these shortcomings and reservations, we felt the high fidelity airway manikin produced many attributes of a difficult laryngoscopic view of the human glottis.
