I wasn’t paying attention as I was in a rush…
Downloaded from TOR website, as advised.
Now my shortcut start-tor-browser opens up in Kate text editor.(facepalm)
How do I reverse my idiocy now?
Properties -> Permissions -> Allow executing file as program
Cannot see such option.
What DE and file manager do you use? Usually you can right-click > Open with… then choose the program and select “Always use this program” or something similar.
I presume you mean a link to the program in a panel, menu or on desktop?
I get a checkbox on right-click → Properties:
⌷ Is executable
I’m using KDE as I guess you are as you have Kate.
… But see the 
comment by @mbb re. Open With.
I somehow didn’t think it would work this way, I located the folder, picked start-tor-browser and voila!