The most common and most likely answer to this crossword clue is the 7 letter word AZURITE
I've seen this crossword clue in Financial Times
A
Z
U
R
I
T
E
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 = azurite.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 AZURITE mean?
AZURITE noun- A blue vitreous mineral; a basic copper carbonate, with the chemical formula Cu2+3(CO3)2(OH)2.