The phrase "a singular role in" is correct and usable in written English.
It can be used to describe a unique or specific function or position that someone or something holds within a particular context or situation.
Example: "The scientist played a singular role in the discovery of the new vaccine, leading the research team through critical phases of development."
Alternatives: "a unique position in" or "a distinct function in".
From then on, it played a singular role in news and entertainment.
"We have a singular role in terms of explaining things to our audience.
Mr. Hunt said the university plays a singular role in the region.
According to Michael Friedberg, a lawyer and watch connoisseur who moderates Timezone.com, a watch aficionados' Web site, "It's a question of how large can you go?" Watches occupy a singular role in the pantheon of male vanity.
The Hebrew Union College-Jewish Institute of Religion community mourns the passing of a great Jewish leader whose love for the Jewish people and vision played a singular role in advancing Jewish education and leadership.
Divākarapaṇḍita played a singular role in Cambodian history, for it was at his urging that Suryavarman II began construction of the temple of Angkor Wat, one of the world's largest religious edifices and certainly one of the greatest achievements of ancient Khmer, or Cambodian, civilization.
Consultants like Shrum — and like Karl Rove, who oversees the Bush-Cheney campaign — play an increasingly singular role in modern politics.
This challenges the notion that miR-10b exclusively performs a singular role of either promoting cell invasion or cell growth.
"Netanyahu doesn't simply go against these institutions and tries to annihilate them, he is motivated by a belief in his singular role in Jewish history.
In this case, therefore, bacterial genetics plays a clear but not singular role in pathogenicity.
Fidel Castro's future is considered a very delicate affair, analysts say, given his singular role in running the country.
