The unclued lights, including one of two words, comprise two adjectives and six  nouns. All share a common origin and are confirmed in Chambers.
 

Across

11    Prelude not quite within 24 hours (7)
12    Seen dancing without my extra turns (7)
14    Kind of horse judge impounds (6)
16    Number in Bow with many sponges (9)
18    Short cassock could make gear for bishops (6)
20    Good ruler following pro criminal (6)
22    Tailoring dress with a rag is concerning (9, two words)
23    Weaken son in place to study novel (7)
24    Return of prongs I change in Tonga (6)
25    Not half curt in state of disunity (6)
28    Horse...