Notice shadow ends terrible outline? (9)
I believe the answer is:
adumbrate
'outline?' is the definition.
('adumbrate' can be a synonym of 'outline')
'notice shadow ends terrible' is the wordplay.
'notice' becomes 'ad' (both can mean an advertisement).
'shadow' becomes 'umbra' (umbra is a kind of shadow).
'ends' means to remove the middle letters.
'terrible' with its middle taken out is 'te'.
'ad'+'umbra'+'te'='ADUMBRATE'
(Other definitions for adumbrate that I've seen before include "Show faintly, in outline" , "Indicate or describe in a general way" , "Faintly indicate" , "sketch" , "Depict in outline" .)