The most common and most likely answer to this crossword clue is the 9 letter word REJOINDER
I've seen this crossword clue in The Daily Telegraph
R
E
J
O
I
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R
More clues leading to the result REJOINDER
Buddy explains!
The straight part
We know that "response" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case response = rejoinder.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 REJOINDER mean?
REJOINDER noun- The defendant's answer to the replication.
- A response that answers another response.
- A quick response that involves disagreement or is witty, especially an answer to a question.
- Re-insertion, typically after allowance of a patent application, of patent claims that had been withdrawn from examination under a restriction requirement.
- To issue a rejoinder.
- To say as a rejoinder.