The most common and most likely answer to this crossword clue is the 11 letter word FOREFATHERS
I've seen this crossword clue in The Daily Telegraph
F
O
R
E
F
A
T
H
E
R
S
Buddy explains!
The straight part
We know that "predecessors" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case predecessors = forefathers.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 FOREFATHERS mean?
FOREFATHERS noun- Ancestor.Wp
- Cultural ancestor; one who originated an idea or tradition.