Rail (7)
'rail' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for barrier that I've seen before include "Checkpoint Charlie, say" , "Impediment" , "Gate" , "'Blockade, fence (7)'" , "It impedes free movement" .)
'rail' is the definition.
(I've seen this in other clues)
This is the entire clue.
(Other definitions for bar that I've seen before include "whose moaning Tennyson hoped to prevent?" , "Barristers - band" , "Prohibit; pressure unit" , "Obstacle" , "Rigid rod" .)