The most common and most likely answer to this crossword clue is the 5 letter word VAUNT
I've seen this crossword clue in The Daily Telegraph
V
A
U
N
T
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 VAUNT mean?
VAUNT noun- A boast; an instance of vaunting.
- To speak boastfully.
- To speak boastfully about.
- To boast of; to make a vain display of; to display with ostentation.
- The first part.