The axis supplies a 0-1 range, so clamping them to 0-1 will do nothing at the moment. What you need is for both of them to be in communication with each other, so that if move forward is at 0.8, move right gets clamped to 0.2. that should limit overall movement to 1. not at my pc right now so I can’t test, but if you take the move forward axis, invert it, and plug it into the max of the move right, as the number gets larger on that axis, the clamp will get lower, slowing movement. repeat for move right axis to move forward clamp max. You will need some more math in there so that the player can still transition to diagonal from full run though, Sort of like a priority to move right that always slows move forward. (or it might work out of the box)
Edit: for the inversion, the “map range clamped” node will do it, axis value goes to the main pin, then in the input fields type 0 and 1 and on the output fields type 1 and 0. now 1 will = 0 and vice versa.