The most common and most likely answer to this crossword clue is the 6 plus 3 plus 5 letter word MURDER SHE WROTE
I've seen this crossword clue in The Daily Telegraph
M
U
R
D
E
R
S
H
E
W
R
O
T
E
Buddy explains!
The straight part
We know that "US TV series" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case us tv series = murder she wrote.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.