Bet this is a first ;)

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Across
  1. 3. Starting point of Philippides' last 26+ mile run.
  2. 4. Millennial mixer.
  3. 5. NHS founder.
  4. 7. Floral cause of 17th Century Dutch speculative bubble.
Down
  1. 1. Zombie dance anthem of 1983.
  2. 2. Skilled crossword solver.
  3. 6. Can be tempered, or popular podcast host.