This is probably for chambered cairn completists only unless you enjoy puzzles - which is what this is.
First up, the site can claim neolithic connections since the butt of a broken polished stone axehead was found here in 1954.
So is it a Clyde cairn? Well it overlooks the Clyde but that's about the best you can say about this jumble of stones.
The most prominent stone, 1.6m high, has been described as a portal stone. It is however triangular which is not normal for portal stones. They're normally square or rectangular. That's problem number one.
Problem number two is that the remaining stones lie in a scatter to the N of this supposed portal stone which would give the site a roughly S orientation. Clyde cairns lie in the N to SE range.
Better just to enjoy the view, I think.
Leave Cardross by Carman Road. Head up hill and park just after the cattle grid. Walk up onto the moor and SW towards the field wall. Eventually, the big pointy portal will come into view. After the wall, there's a fence/gate to cross.