Playwright succeeded with horror story (8)
I believe the answer is:
schiller
'playwright' is the definition.
(Friedrich Schiller)
'succeeded with horror story' is the wordplay.
'succeeded' becomes 's' (genealogical abbreviation).
'with' says to put letters next to each other.
'horror story' becomes 'chiller'.
's'+'chiller'='SCHILLER'
(Other definitions for schiller that I've seen before include "German writer" , "German author" , "German dramatist (Maria Stuart, Wallenstein etc.)" , "German poet and playwright" , "Author of Ode to Joy" .)