The most common and most likely answer to this crossword clue is the 7 letter word POLYMER
I've seen this crossword clue in The Times
P
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L
Y
M
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Buddy explains!
The straight part
We know that "compound" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case compound = polymer.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 POLYMER mean?
POLYMER noun- A long or larger molecule consisting of a chain or network of many repeating units, formed by chemically bonding together many identical or similar small molecules called monomers. A polymer is formed by polymerization, the joining of many monomer molecules.
- A material consisting of such polymer molecules.