eslHQ - clarify

This doesn't make sense at all. It's not grammatical and means nothing. To clarify is a transitive verb and means to make something clear. Eg :

The students obviously don't understand the use of the present perfect so I'll try and clarify it in the next lesson.

Here are some examples from the passive - notice that the object of the active verb (the "something") becomes the subject of the passive verb :

This difference is readily clarified by referring to Table 1.

This connection was clarified by Smith and Smith (1922), who showed that ...

Such legislation was clarified and extended from time to time thereafter. In 1913...

... when the norms were clarified and made more precise

It's not possible therefore to use it as a passive imperative which would need a personal subject. It means nothing.

I think what the writer means could be something like : Please note that this university is closed...
but as always, without the context it's impossible to interpret it accurately.