The most common and most likely answer to this crossword clue is the 11 letter word COMPROMISES
I've seen this crossword clue in The Daily Telegraph
C
O
M
P
R
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More clues leading to the result COMPROMISES
Buddy explains!

The straight part
We know that "concessions" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case concessions = compromises.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 COMPROMISES mean?
COMPROMISES noun- The settlement of differences by arbitration or by consent reached by mutual concessions.
- A committal to something derogatory or objectionable; a prejudicial concession; a surrender.
- In data security, a violation of the security system such that an unauthorized disclosure or loss of sensitive information may have occurred, or the unauthorized disclosure or loss itself.
- To bind by mutual agreement.
- To adjust and settle by mutual concessions; to compound.
- To find a way between extremes.
- To pledge by some act or declaration; to endanger the life, reputation, etc., of, by some act which can not be recalled; to expose to suspicion.
- To cause impairment of.
- To breach (a security system).