Untouched piano key (7)
I believe the answer is:
natural
This clue is a double definition.
'untouched' is the first definition.
(I've seen this in another clue)
'piano key' is the second definition.
(as opposed to a sharp or flat)
(Other definitions for natural that I've seen before include "Unrefined person" , "Innate, inborn" , "Normal; not man-made" , "lacking sophistication" , "Unspoilt" .)