Desirable to remove adhesive core off sleeper's support (4,3)

I believe the answer is:

rail bed

I'm a little stuck... Click here to teach me more about this clue!

'desirable' is the definition.
Both the definition and answer are adjectives.
Perhaps you can see an association between them that I can't see?

I don't understand the rest of the clue.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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.