The phrase "a principal one" is correct and usable in written English.
It can be used to refer to something that is of primary importance or significance in a particular context.
Example: "Among the various factors influencing the decision, cost was a principal one."
Alternatives: "a key one" or "a major one".
Mr. Tom is not a principal one would normally suspect of anxiety.
There are several reasons for this, but a principal one has been lack of a suitable circuit in a good-sized metropolitan area.
"It was a human rights nightmare," he said, emphasizing a reason that was not a principal one the administration articulated before the war, but has become so since.
A principal one, an informed source says, was aluminum oligarch and Putin favorite Deripaska, who at the time was barred from entering the US due to concerns about organized crime links.
People voted Lib Dem for a small number of reasons, a principal one being free higher education.
As shown in Figure 1(a), for instance, two subpopulations appear to be present, a principal one with k s values ranging from almost zero to 0.005 h−1 per unit of creatinine clearance and another small one with values ranging from about 0.033 to 0.039 h−1 per unit of creatinine clearance.
Zack (no last name) is a principal on "One Ocean View," the Fire Island reality series that begins tonight on ABC.
If you have previously thought of going in another direction, now may be the time to do so, said Sean O'Neil, a principal of One to One Leadership, a recruiting and leadership training firm in Pelham, N.Y.
Before 1940 most of the world production of hydrogen was made by processes based on coal or coke, the principal one being a water gas reaction between steam and red-hot coke: H2O + C → CO + H2.
In principal, one licence per owner, but a licence for a backup vehicle is common.
Results showed that there is a significant influence of the upstream building on the wind characteristics above the principal one.
