The most common and most likely answer to this crossword clue is the 7 letter word REAGENT
I've seen this crossword clue in The Times
R
E
A
G
E
N
T
More clues leading to the result REAGENT
- Chemical for testing is concerning a good man
- Test substance of date shown in lease
- Noted factor in chemical test substance
- Chemist may use this ruler, boxing in area
- Test chemical engineers by proxy
- Chemical substance spy used against sappers?
- For example, a back payment covers substance for lab experiment?
- Time to block payment for chemical
- Tester’s torn, broken by time
- . Substance used in test run on key worker
Buddy explains!
The straight part
We know that "Test substance" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case test substance = reagent.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 REAGENT mean?
REAGENT noun- A compound or mixture of compounds used to treat or test materials, samples, other compounds or reactants in a laboratory or sometimes an industrial setting.