This porn should be buried in the earth (4-4)

I believe the answer is:

hard-core

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

'this porn should' is the definition.
The answer and definition are not the same part of speech.

'buried in the earth' is the wordplay.
'buried' becomes 'hard' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in the earth' becomes 'core' ('core' is part of 'earth').
'hard'+'core'='HARD-CORE'

'be' acts as a link.

Can you help me to learn more?

(Another definition for hard-core that I've seen is " Steadfast".)

I've seen this clue in The Guardian.

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.