The most common and most likely answer to this crossword clue is the 6 letter word KELPIE
I've seen this crossword clue in The Times
K
E
L
P
I
E
More clues leading to the result KELPIE
Buddy explains!

The straight part
We know that "being found in Scottish waters?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case being found in scottish waters? = kelpie.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 KELPIE mean?
KELPIE noun- A malevolent shapeshifting spirit, most often in the form of a horse, believed to haunt the rivers and lochs of Scotland.
- An Australian breed of sheepdog.