Raspberry PI Zero W: Route one specific ip/address from LTE Module to a WIFI Hotspot

We have a Raspberry Pi Zero W where is connected a LTE Module over USB (wwan0). The Raspberry provide a Hotspot over the integrated WLAN module. The Raspberry should configured so that a over WLAN connected device (Tablet, Smartphone ect.) has get no general connection to the internet but can access a defined ip address or better a website and the regarding subpages. A local on the raspberry running webserver must stay also accessable.