### Clue: 1 across installed here, I'm in meltdown (5,4,6)
### Answer: THREE MILE ISLAND 
 ### Explanation: Definition: 1 across
 **Anagram of**(… in meltdown) INSTALLED HERE, I'M.
A WIWD(wordplay intertwined with definition) clue, as that US power station suffered a partial meltdown.