### Clue: Over and over again, interrupting journey north for detective (6)
### Answer: POIROT 
 ### Explanation: Definition: detective
 O(abbrev. for "over" in cricket) **plus**(and) O **separated and contained in**(again, interrupting) **reversal of**(… north, in a down clue) TRIP(a journey).
Answer: Hercule, Agatha Christie's famed detective creation.