The most common and most likely answer to this crossword clue is the 9 letter word COMPOUNDS
I've seen this crossword clue in The Daily Telegraph
C
O
M
P
O
U
N
D
S
Buddy explains!
The straight part
We know that "chemicals" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case chemicals = compounds.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 COMPOUNDS mean?
COMPOUNDS noun- An enclosure within which workers, prisoners, or soldiers are confined
- A group of buildings situated close together, e.g. for a school or block of offices
- Anything made by combining several things.
- A substance made from any combination elements.
- A substance formed by chemical union of two or more ingredients in definite proportions by weight.
- A lexeme that consists of more than one stem; compound word; for example laptop, formed from lap and top.
- A compound locomotive, a steam locomotive with both high-pressure and low-pressure cylinders.
- To form (a resulting mixture) by combining different elements, ingredients, or parts.
- To assemble (ingredients) into a whole; to combine, mix, or unite.
- To modify or change by combination with some other thing or part; to mingle with something else.
- To settle by agreeing on less than the claim, or on different terms than those stipulated.
- To settle amicably; to adjust by agreement; to compromise.
- To come to terms of agreement; to agree; to settle by a compromise; usually followed by with before the person participating, and for before the thing compounded or the consideration.
- To compose; to constitute.
- To increase in value with interest, where the interest is earned on both the principal sum and prior earned interest.
- To worsen a situation.
- Of a horse: to fail to maintain speed.