Across:
   8. Stinky rating (4)
   9,7dn. He helped set up 13 with paler gray weave (5 4)
  10. Online enterprise with, some say, a better return (4)
  11. It's costly to stay in this valley, frighteningly close in around one (8)
  12,28. He helped set up 13 with material usually worsted by spinning cores of fibrous twill lines (6 4)
  13. Go and rudely stare at best known of 25 16 (based on 7-8 approach) (6)
  14. Corrupt P.M., so code written (8)
  16. see 25
  18. Nickname given to 13's early 25 16, a favour ideally reciprocated (7)
  21. Friend and circle singer in 1 home of 13 (4 4)
  23. Irrational 8 for rogue content distributor (6)
  25,16. Seeing her scan haphazardly, help with finding things (6 7)
  27. University where 9 7 and 12 28 met for taking stand outside (8)
  28. see 12
  29. Anger about a variety of products (5)
  30. Return plans for unwanted material (4)
Down:
   1. Large state if Carolina recombined (10)
   2. Somewhat risky, in general: you might get caught doing this to the ball (6)
   3. Age of rogue police, and then the Terminators! (8)
   4. Rush and outrage not odd with enclosed letter being the second last (7)
   5. Getting your plaster stuck up maybe starts with calcium sulfate dihydrate (6)
   6. Tattered robe okay for school celebration (8)
   7. see 9 across
  15. "On the line" (sort of Quito area?) (10)
  17. Digital enhancement of ferrous construction, as shown by Canadian engineer (4 4)
  19. Parent of 13 terrific help at conquering "A, B, ... " (8)
  20. Fellow on the inside conveyed go-ahead (7)
  22. Upset or heal city? (6)
  24. Say no to see fur reform (6)
  26. Learns to strip to make a living (4)