The most common and most likely answer to this crossword clue is the 9 letter word BARRICADE
I've seen this crossword clue in The Guardian
B
A
R
R
I
C
A
D
E
More clues leading to the result BARRICADE
- Creator of Wendy houses not a nice man — block!
- A revolutionary fortification
- An obstruction to prevent the retreat of Irish rebel
- Roadblock perhaps about to block pub outing
- Playwright grasping man who acts badly is obstacle
- Playwright encapsulating rogue fence
- Graduate carried off for obstruction
- Bounder in grip of writer’s block
- Block pub food receiving promotion
- Block uncontrolled access to club... i.e., card properly!
Buddy explains!

The straight part
We know that "block" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case block = barricade.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 BARRICADE mean?
BARRICADE noun- A barrier constructed across a road, especially as a military defence
- An obstacle, barrier, or bulwark.
- (in the plural) A place of confrontation.
- To close or block a road etc., using a barricade
- To keep someone in (or out), using a blockade, especially ships in a port