The phrase "a clear border between" is correct and usable in written English.
It can be used to describe a distinct separation or distinction between two or more entities, concepts, or categories.
Example: "There is a clear border between personal and professional life that should be maintained."
Alternatives: "a distinct line between" or "a definite separation between".
Who can draw a clear border between Tremont and Fordham in the Bronx?
If there ever was a clear border between hip-hop and activist poetry, Saul Williams crashes through it on his album "The Inevitable Rise and Liberation of Niggy Tardust" (niggytardust.com).
When you don't have a clear border between people, when neither is secure in its own space, the border is everywhere and any wrong turn can cost you your life.
Simple: When you have a clear border between rival peoples, when each community is secure in its own space, no wrong turn is dangerous and the border can be easily erased by the opportunities and demands of daily life.
In general, it is difficult to define a clear border between such pulsatile dynamics and negative autoregulation-driven oscillation, especially in experimental measurements.
This is since xenografts have high tumor cellularity and a clear border between the tumor tissue and the normal brain and also distort the normal tissue structure.
Conversely, probably due to the age-related accumulation of amyloid [ 49], distribution in the older HCs was more likely to be unimodal, shifted to the amyloid-positive side, without any clear border between amyloid-positive and amyloid-negative individuals.
Note that he doesn't mention a clear border in the area between "Candahar" and Peshawar, now in Afghanistan and Pakistan respectively — still a problem.
Most of the metastatic masses were stiff with a clear border, except for 2 lesions with an obscure border.
A visible crescent-shaped shadow having a clear border was found in the posterior vitreous.
