Playwright succeeded with horror story (8)
I believe the answer is:
Here is my best explanation:
'playwright' is the definition.
'succeeded with horror story' is the subsidiary indication.
'succeeded' becomes 's' (genealogical abbreviation).
'with' is a charade indicator (letters next to each other).
'horror story' becomes 'chiller'.
(Other definitions for schiller that I've seen before include "German author", "German dramatist (Maria Stuart, Wallenstein etc.)", "Dramatist", "German dramatist/poet", "German writer", "German poet and playwright", "Author of Ode to Joy", "German poet, dramatist; William Tell, Maria Stuart" and "Writer".)