The clue is a synonym.

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Across
  1. 2. chemistry
  2. 6. multiple
  3. 7. shape
  4. 8. follow
  5. 9. group
  6. 10. before
Down
  1. 1. likely
  2. 3. seduce
  3. 4. department
  4. 5. diverse
  5. 6. unchanging