The most common and most likely answer to this crossword clue is the 7 letter word CARBIDE
I've seen this crossword clue in Independent
C
A
R
B
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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 = carbide.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 CARBIDE mean?
CARBIDE noun- Any binary compound of carbon and a more electropositive element
- The polyatomic ion C22−, or any of its salts.
- The monatomic ion C4−, or any of its salts.
- A carbon-containing alloy or doping of a metal or semiconductor, such as steel.
- Tungsten carbide.
- Trivial name for calcium carbide (CaC2), used to produce acetylene in bicycle lamps in the early 1900s.