44.

123456789101112131415161718192021
Across
  1. 1. It's close to a plus
  2. 3. UP Old connection method
  3. 5. I As per #14-Down and #19-Across, it's approximately four light years away from earth, Proxima ___ b
  4. 9. It's approximately 907 kilograms
  5. 10. COMB Black taxi pulled up with ape inside, to make one's hair stand on end! (4-4)
  6. 11. WHITE Fancy the new air? It's virtually colourless
  7. 13. Lack of flesh? Not so much, when it's about former queen (8)
  8. 14. It's virtually published
  9. 15. It's approximately 1.75 pints
  10. 18. It's about old message to renew old connections (6)
  11. 19. Parking on lane sounds like it's close to school in flatland (6)
  12. 20. ABOUT When it's approximately
  13. 21. NETWORKS Old connections?
Down
  1. 2. Nah! It's around Irish apple from ravine (6)
  2. 4. It's virtually the same when taking on two, we hear (10)
  3. 6. Religious teaching backed virtual transport perhaps in Greece ? God, it's close to chaos (6)
  4. 7. BAG Pitcher's mound accessory
  5. 8. It's virtually a greeting (5)
  6. 12. Renew old school ties
  7. 16. It's about old currency notes (7)
  8. 17. It's about former times and a meal we enjoyed then (6)
  9. 20. Keeps out of the way of empty space as it's around (6)