The most common and most likely answer to this crossword clue is the 6 plus 3 letter word BOILED EGG
I've seen this crossword clue in The Guardian
B
O
I
L
E
D
E
G
G
More clues leading to the result BOILED EGG
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.