1.   2. 3. 4.  5. g g 6.  7.  8.
  g g 9.    g 10. 11. 12.   g   g  
13.  14.    15.         
  g   g g 16.    g 17.   g   g  
18.   19.        20.    
  g 21.   g g   g g g g   g g  
22.    23.   24. g 25.   26.   
  g g 27.   g 28.  29.   g 30.   g  
31.  32.     g 33.   34.     
  g 35.    g g g   g   g   g  
36.      37.       38.  
  g   g g g   g   g   g 39.   
40.   41.  42.  43.    44.    
  g g   g 45.     g g   g g  
46.      g 47.         

This grid has many 2-,3- and 4-letter words, which have single word clues listed by length (but out of order) under 'SHORTS'. Three of them are initialisms (eg NHS).

ACROSS

1,6. Heard to be... heard to be... not interested in source of feedback? (8,5)

13. Doctors see them often use anti-viral DNA sloppily (15)

18. A salute: a healing brew briefly available in the Northern Territory (5,10)

22,25. "Not For Sale!" ain't so silly for such a treasure (8,6)

31,33. Romantic South Seas cliche ... newly arranged pairs, and ideals (6,8)

36. Wretched poor ... I'm their hero and historical leader? (7,8)

40. In a flap as modern dance gets award, but deal shattered (15)

46,47. You lead New Guinea before soft, ambitious Charles Stuart (5,9)

DOWN

1. Odd... invested sanely at 14/2 (2.9'1,3)

4. Occupied with -E,-M (2,3)

5. Stuff for the mill? (5)

6. Restriction on noble, ... (5)

7. ... as about return of restriction for certain foreigners (5)

8. Deer about; scant regard having gallium replaced by cobalt in common instrument (7,8)

14. Valid, though roughly expressed (5)

15. Go, spread back into 45-Across with character of Magic Roundabout (6)

19. Eat main mixture to bring to life (7)

20. Expressed Artificial Intelligence with colour (5)

23. He possesses new or renovated ... (5)

26. ... construction; it is let to snob (7)

29. Satisfiable, with no retrospective "if"s in heart (8)

32. Album pours out odd characters for skin disease (5)

34. A fee for coral arrangement (5)

37. Grub's up, but with a couple of character's missing ... some do this to you the wrong way (3,2)

SHORTS

2 : prep band greeting prep railway doctor

3 : distant paddle born vehicle edge garment bristle stop signal title swindle age

4 : double indian tomato apple