If drüben is to be analysed parallel to dr+innen, dr+außen, dr+oben as dr+üben, this would make üben a cranberry morpheme. Just like the cran in cranberry, it does not occur independently and cannot be assigned a meaning.
As far as etymology is concerned, Pfeifer says:
drüben Adv. ‘auf der anderen Seite, jenseits’. In zusammengesetzten Ortsadverbien mit ...
The word that describes a movement across (over) a border, towards the speaker is:
over, across, ... (towards the speaker)
And in southern parts of Germany and in Austria there is also a very similar word that doesn't describe the movement, but the result of this movement:
over here, on this side
This word is rarely used in northern ...
I have found another one: die Waldung.
Regarding its etymology, Wiktionary and Grimm's dictionary claim that Waldung is a collective formation of Wald before the 17th century, which, however, cannot be proven. Grimm's also reveals that it may have been formed by similarity to the earlier word feldung. Interestingly, Feldung would be a candidate word, too, ...
Another, less common, word that might fit your criteria (and that was not found by the script) is die Innung (the guild).
Although it seems that originally there was the verb innen in middle-high German, it is not the case in contemporary German.
I wrote a little Python script (see below) to find candidate words. It takes a dictionary and yields all uppercase words that end on ung unless:
there exists a corresponding lowercase word ending on en, eln, or ern. For example bergen → Bergung, kapseln → Kapselung, mitteln → Mittlung, weigern → Weigerung. The presumed verb must at least have five letters ...
Einige Fremdwörter haben sich den heimischen schwachen Substantiven angeschlossen. Warum?
Die schwachen Substantive sind maskulin und bezeichnen im typischen Fall Personen (oder zumindest Lebewesen). Sie sind seit jeher Teil der deutschen Sprache: ahd. boto Bote, Franko Franke, haso Hase, hêrro Herr.
Man beachte allerdings, daß es im Althochdeutschen noch ...