... smooth, hard and suffocating (8)
I believe the answer is:
hairless
'smooth' is the definition.
(similar in meaning)
'hard and suffocating' is the wordplay.
I cannot quite see how this works, but
'hard' could be 'h' (abbreviation used in pencil classifications) and 'h' is found within the answer.
The remaining letters 'airless' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for hairless that I've seen before include "Furious" , "Bald" , "suffering shock loss" .)