The most common and most likely answer to this crossword clue is the 11 letter word BACTERICIDE
B
A
C
T
E
R
I
C
I
D
E
Buddy explains!
The straight part
We know that "contribution to healthy living" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case contribution to healthy living = bactericide.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 BACTERICIDE mean?
BACTERICIDE noun- Any substance that kills bacteria, especially one that is otherwise harmless.