The most common and most likely answer to this crossword clue is the 11 letter word APPEASEMENT
I've seen this crossword clue in The Times
A
P
P
E
A
S
E
M
E
N
T
Buddy explains!
The straight part
We know that "policy of making concessions" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case policy of making concessions = appeasement.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 APPEASEMENT mean?
APPEASEMENT noun- The state of being appeased; the policy of giving in to demands in order to preserve the peace.