The most common and most likely answer to this crossword clue is the 8 letter word PICKLING
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Buddy explains!
The straight part
We know that "preservation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case preservation = pickling.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 PICKLING mean?
PICKLING verb- To preserve food (or sometimes other things) in a salt, sugar or vinegar solution.
- To remove high-temperature scale and oxidation from metal with heated (often sulphuric) industrial acid.
- (in the Python programming language) To serialize.
- To pour brine over a person after flogging them, as a method of punishment.
- To eat sparingly.
- To pilfer.
- An instance of processing something in brine or other solution.
- A process by which the oxide scale on steel (especially stainless steels) is chemically removed (by strong acids).