Is the goal to add a shortcut within the TextSoap app?
There is no option to assign any hotkey to a cleaner within the app*, but TextSoap does have a QuickClean feature.
This allows you to map applying cleaners to command-1 thru command-9 hotkeys.
Create a Custom Group and add the cleaners you would like to assign.
Next, select Text > Quick Clean > Base Shortcuts On > (your custom group)
Once selected, TextSoap will map the first nine cleaners to the command-1 thru command-9 hotkeys.
This is the quickest and easiest to modify.
Additional options :
Selected System Settings > Keyboard > Keyboard Shortcuts > App Shortcuts
Then add a shortcut and have it apply to a menu item (all cleaners are listed in the Text > Clean with submenu
Use TextSoap Agent > Preferences > Global HotKeys to create a shortcut that applies your cleaner(s).