Fun redefined

[Lammy]

no, I mean on the mix bus output, it's clipping.

I see what you mean now. It doesn't matter. Busses are 64 bit mixer processing in plugin-to-plugin transfer and summing, and 32 bit in internal rtas plugin processing. with plenty of headroom. Scaling down to 24 bit is done at master fader transfer point.
That means: during mixing, in general, if busses are just "touching red" and master tracks are not red, all is good in Protools 10.
cheers