Fabia 2009 1.2 HTP - Possible driveshaft failure

Hi fellow Skoda drivers!

Recently I discovered a loud clunking noise. It's most apparent when I decelerate or when I use minimal throttle, straining the engine very little. When I accelerate normally, it does not sound as often or not as loud. It does, however, clunk when I turn right at slow speeds. Not as much as when engine braking. Thing is, my car was briefly troubleshot by my mechanic, who is a very good mechanic. He wasn't overly sure that it was a faulty driveshaft causing the issue. Due to it, it didn’t feel loose etc. I am not so sure.

What else could be the cause of this? I hope this isn't the end of my car.  

Current mileage in British miles: 174 218 with full service history.