The most common and most likely answer to this crossword clue is the 6 letter word SHRIVE
I've seen this crossword clue in The Times
S
H
R
I
V
E
Buddy explains!

The straight part
We know that "Confess" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case confess = shrive.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 SHRIVE mean?
SHRIVE verb- To hear or receive a confession (of sins etc.)
- To prescribe penance or absolution.
- To confess, and receive absolution.