Suggestion for audio clip fade curve algorithm

Audio clips can be level faded from the beginning or the end.
How about a volume fade that dips in the middle?
One could use this for unobtrusively taming a peak. Yes, the volume envelope works similar to this, but with a clip fade, it would be smoother and you would not have to set nodes. Something like this would be especially useful for applying a volume level decrease curve to a vocal peak for example.
Sonar X4 suggestion??