^^^^^^
At the train station in Andermatt you can get on another train to go up to Oberalppass (maybe a 15 minute train ride). From there, you have access to some good intermediate terrain and can ski down to Sedrun. After skiing there, you take the chair/t-bars back up to Oberalppass, get back on the train heading back to Andermatt and get off at the next station, Natschen, ski around here for a bit and then you can ski all the way back down to Andermatt.

The other option is to get off the train in Andermatt and walk across town to the Gemsstock tram and go skiing up there. Very good terrain on the Gemsstock with lot's of off-piste options if you are so inclined.

Definitely doable as a day trip. Enjoy.