The most common and most likely answer to this crossword clue is the 4 letter word TEAL
I've seen this crossword clue in The Times
T
E
A
L
More clues leading to the result TEAL
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 = teal.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 TEAL mean?
TEAL noun- Any of various small freshwater ducks of the genus Anas that are brightly coloured and have short necks.
- A dark, somewhat bluish-green colour; a dark cyan.
- Having a bluish-green colour