How to emit a signal when its member emits one?

How to emit a signal when its member emits one?

For example, I have a class Document which has a private member QUndoStack
which has a signal cleanChanged(). When the member emits the signal, I
wish the containing class Document emits a signal with the same name or
the signal from the member can be transferred to the containing class.
Thus the outside know cleanChanged happened.