The most common and most likely answer to this crossword clue is the 11 letter word OBSTRUCTION
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The straight part
We know that "embargo" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case embargo = obstruction.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 OBSTRUCTION mean?
OBSTRUCTION noun- The act of obstructing, or state of being obstructed.
- Something which obstructs or impedes, either intentionally or unintentionally
- The condition of having the natural powers obstructed in their usual course; the arrest of the vital functions; death.