The phrase "a single unitary" is correct and usable in written English.
It can be used in contexts where you want to emphasize the idea of something being one cohesive entity or system.
Example: "The organization operates as a single unitary body, ensuring that all departments work together seamlessly."
Alternatives: "a unified entity" or "a singular unit".
Nobody expects a single unitary mayor, nor police force, for Greater Paris.
The Lib-Dem dominated county has just been reorganised into a single unitary authority and when I was there at Easter a lot of people didn't like it.
This practice gave rise to the conviction that fine cooking "fused many layers of flavor into a single, unitary whole, rendering individual ingredients unidentifiable to even sensitive palates".
Most people talk or write about Africa as though it were a single unitary state and appear to be unaware that there are 54 countries (or 58 counting the islands) in this very large continent.
Demands for overt quantitative indices of a drive state produced several alternative means of measurement; however, as in the behaviouristic context referred to above, these often failed to coincide with one another, implying that there must be more than a single unitary force at work.
we see that sex is not a single, unitary, easily-determined feature.
A single monolithic, unitary voice, on the other hand, is anathema to any democratic society.
Given the interflowing streams of class, race, ethnicity, age, sexual orientation, ability, and nationality that shape the complex modalities of social experience, it is unlikely that gender or any other single factor could suffice as a single or unitary focal point.
In 2007, proposals to abolish the district councils in favour of a single Somerset unitary authority were rejected following local opposition.
Local government for the town of Reading is principally provided by the Borough of Reading, a single level unitary authority without civil parishes.
The UCLA Loneliness Scale, despite its multi-item construction, shares with single item measures the characteristic of being unidimensional, restricting the representation of loneliness to a single or unitary phenomenon that varies in intensity rather than in nature (Russell, 1996).
