The unclued lights, including three proper nouns (two of two words), consist of three groups of three words of a kind. Together, the three groups suggest a title; the author (seven letters) must be highlighted in the completed grid. Brewer confirms the thematic elements not in Chambers.

Across

1 It regulates pressure in pub with drunken toast (8)
8 Formerly heartless German painter (4)
13 A feature of religious buildings is long (6)
15 Southern runners – they seem happy (7)
17 After a little time, nothing’s dry (4)
18 50” terrace (5)
19 Idiot is eating a fruit...