The most common and most likely answer to this crossword clue is the 7 letter word DIVORCE
I've seen this crossword clue in The Daily Telegraph
D
I
V
O
R
C
E
Buddy explains!

The straight part
We know that "Split" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case split = divorce.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 DIVORCE mean?
DIVORCE noun- The legal dissolution of a marriage.
- A separation of connected things.
- That which separates.
- To legally dissolve a marriage between two people.
- To end one's own marriage to (a person) in this way.
- To obtain a legal divorce.
- To separate something that was connected.