The most common and most likely answer to this crossword clue is the 4 letter word RAIL
R
A
I
L
More clues leading to the result RAIL
- Grouse seriously could be a wading bird
- Complain furiously as fibber turns up
- Track fibber on the way back
- Bar’s story-teller returned
- Barrier keeping tons off path
- . Person who invents revolutionary form of transport
- Bar, one offering pork pie that’s been recalled
- Half-cut banter in bar
- Protest about method of travel
- Bird one tells stories about
Buddy explains!

The straight part
We know that "Barrier" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case barrier = rail.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RAIL mean?
RAIL noun- A horizontal bar extending between supports and used for support or as a barrier; a railing.
- The metal bar that makes the track for a railroad.
- A railroad; a railway, as a means of transportation.
- A horizontal piece of wood that serves to separate sections of a door or window.
- One of the lengthwise edges of a surfboard.
- A vertical section on one side of a web page.
- A large line (portion or serving of a powdery illegal drug).
- To travel by railway.
- To enclose with rails or a railing.
- To range in a line.
- To criticize severely.
- Any of several birds in the family Rallidae.
- To complain violently (against, about).
- An item of clothing; a cloak or other garment; a dress.
- Specifically, a woman's headscarf or neckerchief.
- (of a liquid) To gush, flow.