The most common and most likely answer to this crossword clue is the 8 letter word CAPSTONE
C
A
P
S
T
O
N
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.
What does CAPSTONE mean?
CAPSTONE noun- Any of the stones making up the top layer of a wall; a coping stone.
- A crowning achievement, culmination or finishing touch.
- To complete as a crowning achievement; to top off.
- To train in the Capstone Military Leadership Program.