Company broadcasting series, 'Horizon' (7)
I believe the answer is:
skyline
'horizon' is the definition.
(synonyms)
'company broadcasting series' is the wordplay.
'company broadcasting' becomes 'sky' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'series' becomes 'line' (line is a kind of series).
'sky'+'line'='SKYLINE'
Can you help me to learn more?
(Other definitions for skyline that I've seen before include "Silhouette or outline of buildings" , "Outline of hills or buildings against firmament" , "Visible horizon" , "City horizon" , "Horizon; like NY's (anag.)" .)