I have a server running, on which an application is running. Now I want to gain a person access to this application only.
Is there a good way to give premissions to just one applicaiton without Terminal Services RemoteApp (TS RemoteApp)
You don't need remoteapp in order to publish a single app, it just makes it easier. Look at a reference guide to the RDP file specification, especially the section on alternative shells.
The following syntax should do it.