Possible Clues:

• One cannot make light of being one over the last of this
• A ponderous mass as part of address for Kensington Palace
• That's you and you over the eight - no light matter
• Importance, oppressive force
• Import
• With such a double, you won't get one over the eight
• Point to a figure of some importance
• Importance of delay in pronouncement
• Gravitational pull
• Importance given to women rowing crew