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.