The most common and most likely answer to this crossword clue is the 5 letter word TRUTH
I've seen this crossword clue in Financial Times
T
R
U
T
H
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 TRUTH mean?
TRUTH noun- True facts, genuine depiction or statements of reality.
- Conformity to fact or reality; correctness, accuracy.
- The state or quality of being true to someone or something.
- Faithfulness, fidelity.
- A pledge of loyalty or faith.
- Conformity to rule; exactness; close correspondence with an example, mood, model, etc.
- That which is real, in a deeper sense; spiritual or ‘genuine’ reality.
- Something acknowledged to be true; a true statement or axiom.
- Topness; the property of a truth quark.
- To assert as true; to declare; to speak truthfully.
- To make exact; to correct for inaccuracy.
- To tell the truth.