The most common and most likely answer to this crossword clue is the 10 letter word TELEVISION
I've seen this crossword clue in The Sunday Telegraph
T
E
L
E
V
I
S
I
O
N
More clues leading to the result TELEVISION
- Box set
- Broadcast live on set involving current set
- Set new levies on it
- It’s one evil fuse box
- Medium for which one English novelist might be adapted
- Set in stone, evil I suspect
- Box of novelties I ordered
- I’ve let son out to purchase one box set
- Set of novelties I flogged
- The entertainment provider lacks fundamental decency in grounding violent side
Buddy explains!

The straight part
We know that "Set" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case set = television.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 TELEVISION mean?
TELEVISION noun- An electronic communication medium that allows the transmission of real-time visual images, and often sound.
- A device for receiving television signals and displaying them in visual form.
- Collectively, the programs broadcast via the medium of television.
- Vision at a distance.
- To watch television.