The most common and most likely answer to this crossword clue is the 15 letter word PALEONTOLOGISTS
P
A
L
E
O
N
T
O
L
O
G
I
S
T
S
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.