How to add short-key for "Add Definition in class.cpp" in Qt Creator

You can press Alt+Enter to open a context menu that contains refactoring actions, which are available at the current cursor position.

This is also mentioned in the documentation under Refactoring C++ Code

Maybe a solution with a macro or something in that direction exists as well.

As proposed by @Robin Karlsson:

You can press Alt+Enter to open a context menu that contains refactoring actions available in the current cursor position.

As mentioned by @Dmitry Volosnykh, the above appears in the documentation (more concretely at Applying Refactoring Actions )