There is a "Replace with Clip" command available as a right click option in the sequence. It's not really a 'mode' though. Is this what you mean?
What does Replace Edit do in FCP or Avid?
In Premiere...one certainly can drop another clip into a timeline to replace a clip that is there... by using a command (that has insert / overlay , edit point options).
Check the Menu.
Right click on the clip in the timeline and go to Replace with Clip.
Make sure you either have a clip selected in the Bin or Source Monitor to replace with.
A quicker way is to grap a clip from the bin, hold alt and drag it onto the clip in the timeline.
It is not quite the same thing. With replace edit you replace the clip in the timeline with a clip in a source monitor, but it will align the frame at cursor position in source monitor with cursor position on the timeline. Very useful in music video editing if you want to align a specific frame with a specific audio punch on the timeline.
Premiere has the same: Replace with Clip from Source Monitor, match frame.
A 3 or 4 point insert or overlay edit would do that but why does Replace with Clip from the Source Monitor not do that as per your request?