The phrase "a clear error" is correct and usable in written English.
It can be used to describe a mistake that is obvious and unambiguous.
Example: "After reviewing the calculations, it was evident that there was a clear error in the final total."
Alternatives: "an obvious mistake" or "a blatant error".
Overruffing would have been a clear error, so he discarded.
Instead he finessed the diamond nine, a reasonable play in other circumstances but a clear error with the diamonds known to be on his right.
The third case, however, was the result of a clear error, and although it took place two decades ago, it still bothers him.
Bixby responds to the question about Bowles-Simpson — but not to the "scorable" thing, which is much more important and represents a clear error on his part.
Wednesday's ruling by Judge Royce C. Lamberth is "a clear error" that should be corrected by the United States Court of Appeals for the District of Columbia Circuit, the Justice Department said in court papers.
"If a clear error of personnel or medical judgment occurred, the defense might be able to make some headway in terms of sentencing," said Eugene R. Fidell, president of the National Institute of Military Justice.
The Times's policy is clear: When an early version of an article contains a clear factual error, that error is fixed in the article itself and, at the same time, a correction notice is added at the end.
There was a small error towards higher observed concentrates for the low concentration solutes (magnesium and calcium), no systematic error for potassium 3 mmol/L and a clear systematic error towards lower observed concentrations for potassium 4 mmol/L.
Exam boards are now allowed to change a mark only if there has been a clear marking error.
Much as I respect Danny Baker, the admittance of brown sauce into his Sausage Sandwich Game is a clear category error.
In other words, the grade will only change if there is a clear marking error rather than a difference of interpretation.
