Hard rubber also called vulcanite used for electrical insulators (7)

I believe the answer is:

ebonite

(Other definitions for ebonite that I've seen before include "something rubbery" , "Rubbery material" , "Bee on it (anag.)" , "Vulcanite" , "vulcanised rubber" .)

I've seen this clue in The Mirror.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.