The most common and most likely answer to this crossword clue is the 4 letter word WRIT
I've seen this crossword clue in The Daily Telegraph
W
R
I
T
More clues leading to the result WRIT
- Run in Oscar Wilde, perhaps for a court order
- Common sense required to enclose right legal document
- Document this large would be plain to see
- Intelligence needed to secure right legal document
- Court order, one producing gags? That’s about right
- Once put down, it can be served
- Comedian receives rare summons
- Briefly transcribe court document
- Document containing intelligence about leader of revolutionaries
- Court order that’s mostly in pen
Buddy explains!

The straight part
We know that "Warrant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case warrant = writ.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 WRIT mean?
WRIT noun- A written order, issued by a court, ordering someone to do (or stop doing) something.
- Authority, power to enforce compliance.
- That which is written; writing.
- To form letters, words or symbols on a surface in order to communicate.
- To be the author of (a book, article, poem, etc.).
- To send written information to.
- To show (information, etc) in written form.
- To be an author.
- (with to) To record data mechanically or electronically.
- (of an exam, a document, etc.) To fill in, to complete using words.
- To impress durably; to imprint; to engrave.
- To make known by writing; to record; to prove by one's own written testimony; often used reflexively.
- To sell (an option or other derivative).