The most common and most likely answer to this crossword clue is the 10 letter word VARIEGATED
I've seen this crossword clue in The Daily Telegraph
V
A
R
I
E
G
A
T
E
D
Buddy explains!
The straight part
We know that "was diversified in colour" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case was diversified in colour = variegated.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 VARIEGATED mean?
VARIEGATED verb- To add variety to something.
- To change the appearance of something, especially by covering with patches or streaks of different colour.
- To dapple.
- Streaked, spotted, or otherwise marked with a variety of color.
- (by extension) Very colorful.