The most common and most likely answer to this crossword clue is the 5 letter word EDWIN
I've seen this crossword clue in Financial Times
E
D
W
I
N
More clues leading to the result EDWIN
- Man taking some red wine
- King hated winter to some extent
- Chap’s losing bet on 2015’s General Election . . . .
- This man‘s Merlot perhaps lacking body? On the contrary
- Man cleaned windows on the inside
- … England would triumph with this fellow
- Anglo-Saxon King of England would shortly triumph
- Editor with Indian disclosed Buzz’s real name
- Wined dancing astronaut
Buddy explains!

The straight part
We know that "King" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case king = edwin.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.