Cryptic Fusion

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Across
  1. 3. Moving forward within most epic creation (4)
  2. 4. Heroine left in sea, adrift (4)
  3. 6. Professional in emailing is creating the first of its kind? (11)
  4. 8. Mourn burnt toast in cold environment (8)
  5. 9. Cruise agency mix up creates new wave hit (6)
Down
  1. 1. Endless fuss over charged particle causes reaction (6)
  2. 2. Pair of blokes becoming chief (7)
  3. 4. Aperol trimmed and spritzed with Uranium to make moon (6)
  4. 5. Food shaped mathematics? Sounds like astrological bull (5)
  5. 7. Toroidal object keeps atoms moving around kinetically....initially....! (7)