The most common and most likely answer to this crossword clue is the 5 plus 2 plus 7 letter word STICK AT NOTHING
I've seen this crossword clue in The Guardian
S
T
I
C
K
A
T
N
O
T
H
I
N
G
More clues leading to the result STICK AT NOTHING
Buddy explains!
The straight part
We know that "Have no scruples" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case have no scruples = stick at nothing.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.