One's surprised when this feature is raised (7)
I believe the answer is:
eyebrow
'one's surprised when this feature is raised' is the definition.
'eyebrow' can be an answer for 'feature' (I've seen this before). I'm not sure about the remainder of the definition.
'one's surprised when this feature' is the wordplay.
'one's surprised' becomes 'ey' (I can't justify this - if you can you should give a lot more credence to this answer).
'when' becomes 'e' (I've seen this in other clues).
'this feature' becomes 'brow' (brow is a kind of feature).
'ey'+'e'+'brow'='EYEBROW'
Can you help me to learn more?
(Other definitions for eyebrow that I've seen before include "It is raised in doubt or surprise" , "Facial feature" , "Penthouse, for example" , "hairpiece" , "Hirsute growth above optic" .)