The most common and most likely answer to this crossword clue is the 6 plus 3 plus 7 letter word BOXING THE COMPASS
I've seen this crossword clue in The Guardian
B
O
X
I
N
G
T
H
E
C
O
M
P
A
S
S
Buddy explains!
The straight part
We know that "that involves a complete turnaround" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case that involves a complete turnaround = boxing the compass.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.