The most common and most likely answer to this crossword clue is the 7 letter word LATICES
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Buddy explains!
The straight part
We know that "Rubbery materials" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rubbery materials = latices.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 LATICES mean?
LATICES noun- A clear liquid believed to be a component of a humour or other bodily fluid (esp. plasma and lymph)
- The milky sap of several trees that coagulates on exposure to air; used to make rubber.
- An emulsion of rubber in water, used in adhesives and the like.
- Natural latex rubber, especially non-vulcanized rubber, such as is used in making latex gloves, latex condoms, and latex clothing.