"a leeway" is correct and usable in written English.
It is typically used to refer to the amount of freedom or flexibility allowed in a situation or decision-making process.
Example: "The manager gave the team a leeway in their project deadlines to accommodate unforeseen challenges."
Alternatives: "some flexibility" or "a margin of error".
Clairaut was finally able to predict in the fall of 1758 that Halley's Comet would reach perihelion in April 1759, with a leeway of one month.
She paid the equivalent of $100, and received from him a receipt for $60, giving herself a leeway of $40 for other duty-free purchases.
The cull is happening to try to make all the new seats, apart from a handful of exceptions, contain somewhere near the average number of voters, a figure of 74,679, with a leeway of just 5% above or below.
It deadlocked, 7-7, on a plan calling for a 50-50 split of male and female athletes, regardless of the student body makeup, with a leeway of 2 to 3 percentage points.
He is 23 years old, plays for Ajax in the Netherlands, and he had to know there was a leeway in the law of soccer that allowed him to take a red card, an automatic expulsion and banishment from at least the next match.
In a general way, they are based on correlations with Egypt, where, from the beginning of the Early Dynastic period (c. 2925 bc onward), a historical chronology can be established with a leeway of a few centuries and can be fixed within reasonably narrow limits after about 2000 bc.
But a little leeway for a huge Hollywood veteran in front of a global audience might have been more suitable".
So I presume they have a greater leeway to be a little more generous".
Now with Messenger approaching a billion users, Facebook has a little leeway.
But I want to give ourselves a little leeway in case he needs an extra day.
When you're eating 18 dinners a week, I figure you deserve a little leeway".
