Learn Finnish: Vastustuksen takia kaavoituksesta tehtäneen kompromissi. - Because of the opposition, a compromise will probably be made about the zoning.

It is the passive potential form of the verb tehdä (to make). It is formed by applying the passive potential marker -täneen (the front-vowel version of -taneen) to the verb stem. The potential mood expresses probability or uncertainty, which is why it translates to "will probably be made".

Why is the object kompromissi in the nominative case instead of the genitive?

In standard Finnish, the total object of a passive verb is always in the nominative case rather than the genitive-accusative. Since tehtäneen is a passive verb and making a compromise is seen as a complete action here, the base form kompromissi is used.

Why does kaavoituksesta take the elative (-sta) ending here?

The elative case is often used to mean "about" or "concerning" a topic. Here it shows what the compromise is about, almost as if translating to making a compromise "out of" the zoning.

What is the base word for kaavoituksesta and how is it built?

The base form is kaavoitus (zoning or town planning). It is a noun describing a process, derived from the verb kaavoittaa (to zone or plan), which in turn comes from the noun kaava (a plan, formula, or pattern).