Obstacle, source of danger (6)
I believe the answer is:
hazard
I believe this is a double definition.
'obstacle' is the first definition.
(I know that hazard is a type of obstacle)
'source of danger' is the second definition.
(I've seen this before)
(Other definitions for hazard that I've seen before include "Potential danger" , "Dice game" , "Something dangerous, such as black ice?" , "Danger; gamble" , "Possible source of danger" .)