The most common and most likely answer to this crossword clue is the 15 letter word COUNTERPROPOSAL
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More clues leading to the result COUNTERPROPOSAL
Buddy explains!
The straight part
We know that "a different one" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a different one = counterproposal.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 COUNTERPROPOSAL mean?
COUNTERPROPOSAL noun- A proposal made as an alternative to another, earlier proposal.