Big name in TV ratings (7)
I believe the answer is:
nielsen
'big name in tv ratings' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nielsen that I've seen before include "Danish symphonist" , "Musician" , "Carl -, Danish cmpsr." , "Danish composer, Carl (1865-1931)" , "Leslie --, Canadian actor" .)