### Clue: Rough old invader, say, behind horse one's ridden (6,8)
### Answer: HARLEY DAVIDSON 
 ### Explanation: Definition: one's ridden
 **Anagram of**(Rough) [OLD INVADER, SAY] **placed below**(behind, in a down clue) H(abbrev. for "heroin"/horse in slang).
Defn: An iconic motorcycle make in a classic movie: