Across:
   8. Celebration in singing new lullabies, as extremes of bias removed (8)
   9. They usually have waves on them, as once liquid (6)
  10. Study of entwined connections of life, observations giving you sources (7)
  11. Lives ruined around not having alcohol supplies! (7)
  13. Crazy Roman "adult" venue where patrons often bring several changes of clothing (10)
  14. Sickness caught by elderly (4)
  15. Foolish waste ignoring first letter opposed to 19 (4)
  17. A bit of inclusion embraced by adapting noun "marriage" (5)
  19. Foolish waste ignoring first letter opposed to 15 (4)
  21. see 6 down
  23. One who'll take punts and so tap lucre freely (10)
  25. Conference after mass conflict and mutual assured destruction period returned (7)
  26. Operation 11, for instance, great if ahead of time and securing patch of 2 (7)
  28. Dark sexual demons haunting Spain: Cubists! (6)
  29. Chopped up cane as something to put on cooking fire (8)
Down:
   1. Arranged C.O.D., bleak scenario for 15 2 in early 14 4 drama (8)
   2. Some remember links as city split between 15 and 19 (6)
   3. Swiss peak with development of fungus jar not requiring sealed top (8)
   4. Backward, savage way to resolve disagreement? (3)
   5. Socialism's older leaders struggle with true representative body (6)
   6,21ac. Muck adheres to criminal after abandoning ring (unit the 5 17 didn't want in 2!) (8 4)
   7. Regularly turns wheel, old and sick (6)
  12. How some peoples spread their influence far and wide, i.e. sperm scattering (7)
  16. Eliminates dates? (5 3)
  18. Vernian craft in USA, until disrupted (8)
  20. "Sovereign citizen"? (Often leads with endless confused waffle) (8)
  22. see 27
  23. Left in embarrassment as 5 leader turned nasty (6)
  24. What everyone needs, especially everyone that is small! (6)
  27,22. How to get to Kingdom of Saudi Arabia briefly ... put out some feelers? (3 6)