The most common and most likely answer to this crossword clue is the 12 letter word AROMATHERAPY
I've seen this crossword clue in The Sunday Telegraph
A
R
O
M
A
T
H
E
R
A
P
Y
Buddy explains!
The straight part
We know that "Natural way to treat someone" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case natural way to treat someone = aromatherapy.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 AROMATHERAPY mean?
AROMATHERAPY noun- The use of selected fragrances in lotions and inhalants in an effort to affect mood and promote health.