### Clue: Something sinister locked in extremes of nature for post-apocalyptic writer (5,5)
### Answer: NEVIL SHUTE 
 ### Explanation: Definition: post-apocalyptic writer
Nevil Shute wrote post-apocalyptic novel *On the Beach* 
 **EVIL**="Something sinister" + **SHUT**="locked", all inside the extreme letters of **N**atur**E