Observe line has disturbed facial feature (7)
I believe the answer is:
eyelash
'facial feature' is the definition.
The definition and answer can be both body parts as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'observe line has disturbed' is the wordplay.
'observe' becomes 'eye' (I've seen this before).
'line' becomes 'l'.
'disturbed' indicates anagramming the letters.
'has' with letters rearranged gives 'ash'.
'eye'+'l'+'ash'='EYELASH'
Can you help me to learn more?
(Other definitions for eyelash that I've seen before include "maybe one drops with a wink" , "Hair; cilium (anatomy)" , "A hair in fringe above optic" , "Facial hair, cilium" , "Short facial hair" .)