The most common and most likely answer to this crossword clue is the 9 letter word BACTERIAL
B
A
C
T
E
R
I
A
L
More clues leading to the result BACTERIAL
Buddy explains!

The straight part
We know that "of germs" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case of germs = bacterial.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.
Crossword Answer definitions
BACTERIAL adjective- Of, relating to, or caused by bacteria.