Clipgain like in PT is a lot requested and I would like to see it too. But there is a workaround, not as smooth as you do not see the audio wave changing, but the effect is the same:
Add a Mixtool to the track, click on the gain knob and then on the A in square at the left-top in S1. This creates an automation lane on that track for the mixtool and then you can draw the gain in.