The most common and most likely answer to this crossword clue is the 13 letter word PHYSIOTHERAPY
I've seen this crossword clue in The Daily Telegraph
P
H
Y
S
I
O
T
H
E
R
A
P
Y
More clues leading to the result PHYSIOTHERAPY
Buddy explains!
The straight part
We know that "Treatment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case treatment = physiotherapy.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 PHYSIOTHERAPY mean?
PHYSIOTHERAPY noun- Therapy that uses physical techniques such as massage, ultrasound, heat, and exercise