The most common and most likely answer to this crossword clue is the 4 letter word CITE
I've seen this crossword clue in The Guardian
C
I
T
E
Buddy explains!

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 CITE mean?
CITE verb- To quote; to repeat, as a passage from a book, or the words of another.
- To list the source(s) from which one took information, words or literary or verbal context.
- To summon officially or authoritatively to appear in court.
- A citation