The most common and most likely answer to this crossword clue is the 12 letter word PREDOMINANCE
I've seen this crossword clue in The Sunday Telegraph
P
R
E
D
O
M
I
N
A
N
C
E
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.
Crossword Answer definitions
PREDOMINANCE noun- The condition or state of being predominant; ascendancy, domination, preeminence, preponderance.