Previous solution

Across: 1. Musical chairs 9. Spinnaker 10. Inapt 11. Erred 12. Synthetic 13. Impounds 15. Held up 18. Seethe 20. Passover 23. Underhand 24. Tenon 25. Cadet 26. Groundnut 27. Preternatural.

Down: 1. Mysteries 2. Stirrup 3. Caned 4. Lakeside 5. Haring 6. Irishness 7. Started 8. Antic 14. Usherette 16. Perinatal 17. Hand down 19. Ended up 21. Vintner 22. Bargee 23. Uncle 24. Tenet.