The phrase "a singular piece" is correct and usable in written English.
It can be used to refer to one specific item or element, often in contexts like art, writing, or collections.
Example: "The gallery showcased a singular piece that captured the essence of modern art."
Alternatives: "a unique item" or "an individual piece".
It is a singular piece in more ways than one.
But this time they can rally around a singular piece of history.
I think "Moulin Rouge" is going to be a singular piece of filmmaking.
From each one, she collected lifelong memories and a singular piece of wisdom that formed the person she would become.
Nothing can beat the excitement of collecting a singular piece of data, of measuring it delicately, of pronouncing it fit, and extracting its story.
What I had in my hands was a singular piece of history, a collection of men (Columbia didn't admit women at that time) who had helped shape the American literary canon for a better part of the 20th century.
In any case, it was a unique piece, singular even among the works of an artist for whom singularity was the rule; it could hardly fail to fetch a record price.
Messenger RNA gives us information on effects in gene regulation solely at the level of transcription, which is an important yet singular piece of a complex process.
This film was treated to some hooting and booing on its first screening in Cannes; it is a very odd, singular piece of work: not the visionary masterpiece it assumes itself to be and muddled in its effects and ideas.
The 10-minute exchange was a small slice of the singular piece of American political theater that is a John McCain town-hall-style meeting in New Hampshire.
Presenting a structurally complex video installation (as she has a tendency to do), the central, singular piece by artist Melanie Gilligan at Galerie Max Mayer consists of two cubic monitors embedded into hovering industrial rods.
