The most common and most likely answer to this crossword clue is the 9 letter word ALSATIANS
A
L
S
A
T
I
A
N
S
Buddy explains!
The straight part
We know that "Guard dogs" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case guard dogs = alsatians.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 ALSATIANS mean?
ALSATIANS noun- A native or inhabitant of Alsace.
- (dated US) A German shepherd dog.
- A rogue or debauchee, like those who haunted Alsatia in London.