Strange Noise....clutch related?

The gearbox IMO.

Mine does somewhat similar thing. When you forget that it's a Jimny* and don't pull the stick all the way into reverse then sometimes it feels like the stick 'notched in', the reverse light switch isn't activated though and it isn't 'in gear' properly. It then makes same noise (mine is much quieter) and goes boldly nowhere.

Solution: pull the stick into position properly, all the way (you should be able to feel it, it's like 'half cock' vs 'fully cocked' on the gun, I don't know how to describe it better).

First car, that I've learned to drive in was a 30 years old Skoda S100 with same problem, so I'm well used to it, and ignore it along with many other quirks the car* has. I've, heard, however about problems with engaging reverse (and first gear also, for that matter) in older Jimnys, and that's probably the case with yours as well.

Put the car into reverse and check if the reverse lights are on (assuming that the switch works). If it feels like it's in gear, won't move and whines and the lights are off then try to put in gear properly and see if that works. If it does then you have just sorted the problem, you just need to remember about it. Both the Skoda and the Jimny had it for years without any issues.
If your's worse than this then I'd have it checked by mechanic, pointing at the gearbox as the culprit.

Anyways, what I've colorfuly described above can probably be 'not fully in mesh', I just don't speak the technical lingo well, so I wasn't sure


* look at the signature note

Thanks fshdck, I think you could be right.....it's not done it at all since I've been a little slow with changes to reverse and first.

Reverse lights come on, it may ultimately be the gearbox slowly dying though.

Until it gets any worse I'll need to remember shes an old girl now and take reverse changes with a bit of care!