The unclued lights can be associated with an undisclosed quality. All associations can be found in Brewer and/or Chambers. Alphabetical order takes precedence for the solution at 36D.

Across

9 Having broken rule outside, detective begins to feel guilty (10)
14 Stiff paper, way-out neckwear? (3)
18 Cox for Hereford, perhaps? (5)
20 Choose in calamitous situation whence improvement may be in sight (7)
22 Heading from highland country, look over Shakespearean setting (7)
25 Being drawn to appear in Swindon Town (5, two words)
28 Top of oak stake tipped prime succulent (7)
33 A hammer? Australian has about fifty in stock (7)
37 Run, then walk back to...