1.  2.  3.  4.   g 5. 6.  7.  8.
  g   g   g   g 9. g   g   g  
10.               
  g   g   g   g   g   g   g  
11.       g 12.        
  g   g g g 13. g   g   g g g  
14.    15. g 16.      17.   
g g   g   g   g   g   g   g g
18.          g 19.    20.
  g g g   g   g   g g g   g  
21.  22.       g 23. 24.     
  g   g   g   g 25. g   g   g  
26.               
  g   g   g   g   g   g   g  
27.       g 28.        

ACROSS

1. Me? I stank - badly off the mark. (8)

5. Get up as a hundred finish (6)

10,25-Down. ??? (6,9,4)

11. Very angry fellow writer lost head about nothing (6)

12. Spirit essential to meditate (8)

14. Play for a crisis (5)

16,18. ??? (6,3,9)

19. Aboriginal artefact form the nullarbor? Seems unlikely! (5)

21. Revellers right into bicycle-sharers (8)

26,23. ??? (8,7,6)

27. Hate to unassess perhaps? (6)

28. Spots Him moving in visions of light (8)

DOWN

1. Serious education studied in particular (7)

2. High in "cool", wise about being in one's learning years (6,3)

3. Musical is top-class (on points, that is ... (5)

4. ... otherwise feel selects a piece) (4)

6. On and off, shuts up ... since it owns the theory (9)

7. Musical note ... the relative minor, thanks (5)

8. Dismal place in crap era (7)

9. All around, a limit in good head (9)

13. Cutting it fine to sing around organ (9)

15. A sikh saga about former rulers of Japan? (9)

17. Poor slave girl of the townsfolk (9)

18. Sprinkled weed bed all over (7)

20. Dire Straits? (7)

22. A little land is rented (5)

24. Zero component genre? (2-3)

25. see 10-Across