The most common and most likely answer to this crossword clue is the 4 plus 6 letter word POST CHAISE
I've seen this crossword clue in Independent
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More clues leading to the result POST CHAISE
Buddy explains!
The straight part
We know that "Coach" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case coach = post chaise.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 POST CHAISE mean?
POST CHAISE noun- An enclosed horse-drawn carriage with four wheels, used to transport mail and passengers.