Funny I've just came on looking for this same issue, mines when turning continuously like when turning onto a driveway slowly. Mines lowered if that helps.
The front ARB may hit the control arm when lowered. This is a known issue and if this is the case with you, than you need adjustable tie rods.
Other possible reasons:
- the bracket/s that are holding the front ARB in place are loosen
- the ARB bushes are worn
- the tie-rods are worn
- the steering rack has a problem
- the top mounts are worn
- the bearings are worn
- the drive shaft/s joint/s are worn
May be some other causes but these are the most frequent.
That's exactly what mine is like.
Noticed it the other day when slowly turning onto the drive. It does it all the time though, you can hear it when turning round a corner slowly.
I have Eibach sportlines on mine but don't think that will make any difference.