If TORA = TODA then the mass is limited by TODA because the aircraft must be at 35ft at the end of TODA with an engine out. (The V1 will be established on TODA and ASDA)

If we now have a clearway then TODA is increased and I don't need to be at 35ft until a later point at the end of TODA.

The FLLTOM increases.

As the ASDA has stayed the same then the V1 must be reduced for the stop case.

Remember V1, the decision speed, is the point where I can safely reject the take off and stop within ASDA and the point where I can commit to take off with an engine out and make 35 ft within TODA.