### Clue: Organ certain to turn up under urologist's coat (6)
### Answer: UTERUS 
 ### Explanation: Definition: Organ
 **Reversal of**(… to turn up, in a down clue) SURE(certain;doubtless) **placed below**(under, in a down clue) **the 1st and last letters of**(…'s coat;covering) "urologist".