Obstacle (6)
'obstacle' is the definition.
(barrier is a kind of obstacle)
This is the entire clue.
(Other definitions for barrier that I've seen before include "Object blocking passage" , "It impedes free movement" , "Fence; obstacle" , "Blockade, railing" , "Construction to contain, say, crowds" .)
'obstacle' is the definition.
(I know that hurdle is a type of obstacle)
This is all the clue.
(Other definitions for hurdle that I've seen before include "Barrier (to be jumped)" , "Obstacle to jump" , "'Obstacle, in a race perhaps (6)'" , "Obstacle to be jumped over in race" , "Obstacle used in races" .)