The most common and most likely answer to this crossword clue is the 13 letter word Y-CHROMOSOMES
I've seen this crossword clue in Financial Times
Y
-
C
H
R
O
M
O
S
O
M
E
S
Buddy explains!
The straight part
We know that "One of them to a cell is the norm among monks" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one of them to a cell is the norm among monks = y-chromosomes.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.