A feature of intellectual broadcast from London (7)
I believe the answer is:
eyebrow
'a feature' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
(Other definitions for eyebrow that I've seen before include "What's raised in surprise" , "It's lifted in surprise" , "Facial hair (that can be raised)" , "surprisingly elevated" , "this might be raised in surprise" .)