Shearing only working on the 2 axis I don't want I am making some sort of underground subway inspired by a blender guru tutorial, and I used f-spy to mark out the axis etc. and that worked fine when I imported it in. I positioned a plane and extruded it up. There was a turn in the subway so I want to shear the end of the extruded plane. When I shear something, it always says, in the information in top left, that I can shear it in the x or y axis, as you can see here.

Image 1
Is there any way of shearing on the z axis? I have come across this issue many times before.
Obviously I could just rotate it, like 
this, but the rotating creates this tapered effect. I would like to do it by shearing if that's possible.
Thanks for your time.
By default the Shear tool axis will be the one of the view, for example if the view is this one, the X and Y axis will be these ones:

So if you keep the default Orientation and shear on the X axis, the view will be the axis and the vertices will move along the view's X axis, like this:

But you can also choose to shear on the Global, Local axis, etc... You need to choose the Orientation in the Operator box. In this box, the Axis will be the rotation pivot axis, the Axis Ortho will be the axis along which the vertices move, the Offset will be the amount of units they move.

In your case you can either put your view on top (7) and shear on the Y axis, or stay in user view, press ShiftCtrlAltS to shear, press Enter right away, and in the Operator box, switch the Orientation to Global, Axis &gt; Z, Axis Ortho &gt; Y.