Note planet discovered by a student is untouched by human hand (7)
I believe the answer is:
natural
'note planet' is the definition.
'natural' can be an answer for 'note' (I've seen this before). I'm unsure of the 'planet' bit.
'by a student is untouched by human hand' is the wordplay.
'by' says to put letters next to each other.
'a student' becomes 'L' (as in L-plates for learner drivers).
'is untouched by human hand' becomes 'natura' (I can't explain this - if you can you should give a lot more credence to this answer).
'l' after 'natura' is 'NATURAL'.
'discovered' acts as a link.
Can you help me to learn more?
(Other definitions for natural that I've seen before include "Artless, unaffected," , "certain to succeed" , "Simpleton" , "Normal; not sharp or flat" , "Normal - innate - instinctive" .)