The most common and most likely answer to this crossword clue is the 6 letter word MAROON
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More clues leading to the result MAROON
Buddy explains!

The straight part
We know that "Colour" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case colour = maroon.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 MAROON mean?
MAROON noun- An escaped negro slave of the Caribbean and the Americas or a descendant of escaped slaves.
- A castaway; a person who has been marooned.
- To abandon in a remote, desolate place, as on a desert island.
- Associated with Maroon culture, communities or peoples.
- A rich dark red, somewhat brownish, color.
- Of a maroon color
- A rocket-propelled firework or skyrocket, often one used as a signal (e.g. to summon the crew of a lifeboat or warn of an air raid).
- An idiot; a fool.