The most common and most likely answer to this crossword clue is the 9 letter word DALMATIAN
I've seen this crossword clue in The Times
D
A
L
M
A
T
I
A
N
More clues leading to the result DALMATIAN
- Dog frantically tailed a man dumping drug
- At sea, aim at land one’s spotted
- Kid turning, runs away from alien one's spotted
- One’s spotted wagging tail and guarding master
- One’s spotted fiddle involving Labour leader in Mr Brown
- Animal spotted barking at animal with spotted tail
- Split personality?
- One spotted bringing coaster into Chinese port
- Daughter, upset at animal, spotted one
- Play with a mad latin dog
Buddy explains!

The straight part
We know that "one's spotted" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one's spotted = dalmatian.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 DALMATIAN mean?
DALMATIAN noun- One of a breed of dog with a short, white coat with dark spots.
- (demonym) A native or inhabitant of Dalmatia.