The most common and most likely answer to this crossword clue is the 15 letter word SELF-DISCIPLINE
S
E
L
F
-
D
I
S
C
I
P
L
I
N
E
Buddy explains!
The straight part
We know that "controlling one's own impulses/" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case controlling one's own impulses/ = self-discipline.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 SELF-DISCIPLINE mean?
SELF-DISCIPLINE noun- Control of oneself, willpower.