Related Clues:

• First of a kind
• Thrusting, ambitious type
• Duke, perhaps, hosts one about to become an explorer
• One in landing-place is explorer
• Part of bridge - holding ace, take the lead
• Person running errands for a ruthless tycoon?
• Cask full of oxygen always needed for spacecraft
• Giant dog decapitated aggressive person
• Lead the way round one pillar
• Seaside feature includes one for the first time in the field
• In post, I break new ground
• Open up post containing a joke
• Mole interrupted by a certain person arriving early
• Enterprising person's giant missive not opened
• As a ground-breaker, I would need to be surrounded by support