The most common and most likely answer to this crossword clue is the 6 letter word TACKED
I've seen this crossword clue in The Guardian
T
A
C
K
E
D
More clues leading to the result TACKED
- In conversation, discretion is nailed
- So-called diplomacy changed course
- Went about enunciating what diplomats require
- Changed one’s position with pronounced diplomacy
- Fixed with diplomatic handling, reportedly
- Changed course due to careful handling, say
- Changed course due to report of diplomacy
- Changed course and joined...
- Changed direction of diplomacy in speech
- Joined Grace in chorus
Buddy explains!

The straight part
We know that "changed course" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case changed course = tacked.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 TACKED mean?
TACKED verb- To nail with a tack (small nail with a flat head).
- To sew/stich with a tack (loose seam used to temporarily fasten pieces of cloth).
- To maneuver a sailing vessel so that its bow turns through the wind, i.e. the wind changes from one side of the vessel to the other.
- To add something as an extra item.
- Often paired with "up", to place the tack on a horse.
- To nail with a tack (small nail with a flat head).
- To sew/stich with a tack (loose seam used to temporarily fasten pieces of cloth).
- To maneuver a sailing vessel so that its bow turns through the wind, i.e. the wind changes from one side of the vessel to the other.
- To add something as an extra item.
- Often paired with "up", to place the tack on a horse.