The most common and most likely answer to this crossword clue is the 4 letter word BUND
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More clues leading to the result BUND
Buddy explains!

The straight part
We know that "embankment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case embankment = bund.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 BUND mean?
BUND noun- A league or confederacy; especially the confederation of German states.
- A secondary enclosure, typically consisting of a wall or berm, which surrounds a tank or fluid-handling mechanism, intended to contain any spills or leaks.
- A perennial ("wet") or seasonal ("dry") pond constructed in a depression and in which fish are stored, typically for breeding.
- To provide berms or other secondary enclosures to guard against accidental fluid spills within.