The most common and most likely answer to this crossword clue is the 5 letter word BURGH
B
U
R
G
H
Buddy explains!
The straight part
We know that "Scottish town once" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case scottish town once = burgh.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 BURGH mean?
BURGH noun- A small mound, often used in reference to tumuli (mostly restricted to place names).
- A borough or chartered town (now only used as an official subdivision in Scotland).