The most common and most likely answer to this crossword clue is the 5 letter word BARDO
B
A
R
D
O
Buddy explains!
The straight part
We know that "‘the precursor to rebirth’" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ‘the precursor to rebirth’ = bardo.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 BARDO mean?
BARDO noun- The state of existence between death and subsequent reincarnation.