The most common and most likely answer to this crossword clue is the 3 plus 4 letter word SKY BLUE
I've seen this crossword clue in The Guardian
S
K
Y
B
L
U
E
More clues leading to the result SKY BLUE
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 = sky blue.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 SKY BLUE mean?
SKY BLUE adjective- Of a vibrant light blue colour, like that of the sky on a fine day.