In previous versions of Photoshop I have been able to use any brush type with the Clone Stamp Tool.
In Photoshop CC 2018 the only brush option seems to be a round brush with variables of size and softness. When I try and select another brush it takes me to another tool (eg the standard brush tool for painting)
Is there a way to use any brush type with the Clone Stamp Tool?
Yes you can. However some brushes are saved with an associated tool settings so when selected they switch to that tool. You can see which ones by turning on "Show Additional Preset Info" in the brushes panel. The tool is then shown at the top right of the brush.
To save a copy of a brush without the tool preset then with the brush selected, choose New Brush Preset, from the menu above, and in the dialogue uncheck "Include Tool Settings"
You will now have the same brush available to use with any tool