The most common and most likely answer to this crossword clue is the 15 letter word CRYSTALLIZATION
C
R
Y
S
T
A
L
L
I
Z
A
T
I
O
N
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.