The most common and most likely answer to this crossword clue is the 8 letter word INSTINCT
I've seen this crossword clue in The Daily Telegraph
I
N
S
T
I
N
C
T
More clues leading to the result INSTINCT
- Feeling cold during hot spell
- Intuitive feeling of Conservative opening popular allocated work
- Tintin’s struggling with Haddock’s sixth sense
- Sense criminal isn’t attending court
- Intuition shown by Sussex County openers appearing in two internationals
- Di abandons hazy intuition
- Charged this month in court
- Cool colour preserves special feeling
- Bee, possibly short of energy, keeps egg back, having a gut feeling
- Gut feeling you’ll need this month in court
Buddy explains!

The straight part
We know that "Natural impulse" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case natural impulse = instinct.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 INSTINCT mean?
INSTINCT noun- A natural or inherent impulse or behaviour.
- An intuitive reaction not based on rational conscious thought.
- Imbued, charged (with something).