I don't know how much utility you can achieve with this, but I suppose
you could do it with a macro. Select the text and run:

Sub Scratchmacro()
Dim oRng As Word.Range
Dim pText As String
Set oRng = Selection.Range
pText = oRng.Text
oRng.Delete
oRng.Fields.Add oRng, wdFieldEmpty, pText
End Sub