The most common and most likely answer to this crossword clue is the 5 letter word WRACK
I've seen this crossword clue in The Times
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R
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K
More clues leading to the result WRACK
Buddy explains!

The straight part
We know that "Destruction/marine vegetation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case destruction/marine vegetation = wrack.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 WRACK mean?
WRACK noun- Vengeance; revenge; persecution; punishment; consequence; trouble.
- (except in dialects) Ruin; destruction.
- The remains; a wreck.
- To execute vengeance; avenge.
- To worry; tease; torment.
- To place in or hang on a rack.
- To torture (someone) on the rack.
- To cause (someone) to suffer pain.
- To stretch or strain; to harass, or oppress by extortion.
- To put the balls into the triangular rack and set them in place on the table.
- To strike a male in the testicles.
- To (manually) load (a round of ammunition) from the magazine or belt into firing position in an automatic or semiautomatic firearm.
- To move the slide bar on a shotgun in order to chamber the next round.
- To wash (metals, ore, etc.) on a rack.
- To bind together, as two ropes, with cross turns of yarn, marline, etc.
- (structural engineering) Tending to shear a structure (that is, force it to move in different directions at different points).
- To stretch a person's joints.
- To drive; move; go forward rapidly; stir
- To fly, as vapour or broken clouds
- To clarify, and thereby deter further fermentation of, beer, wine or cider by draining or siphoning it from the dregs.
- (of a horse) To amble fast, causing a rocking or swaying motion of the body; to pace.
- Remnant from a shipwreck as washed ashore, or the right to claim such items.
- Any marine vegetation cast up on shore, especially seaweed of the genus Fucus.
- Weeds, vegetation or rubbish floating on a river or pond.
- A high flying cloud; a rack.
- To wreck, especially a ship (usually in passive).