The most common and most likely answer to this crossword clue is the 8 letter word TELEPLAY
I've seen this crossword clue in Financial Times
T
E
L
E
P
L
A
Y
Buddy explains!
The straight part
We know that "Something to watch on the box" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case something to watch on the box = teleplay.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does TELEPLAY mean?
TELEPLAY noun- (authorship) A script formatted like a screenplay, but written to be made into an episode of a television show.