The most common and most likely answer to this crossword clue is the 8 letter word CLEANSED
I've seen this crossword clue in Financial Times
C
L
E
A
N
S
E
D
More clues leading to the result CLEANSED
Buddy explains!

The straight part
We know that "missing the filthy bits?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case missing the filthy bits? = cleansed.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 CLEANSED mean?
CLEANSED verb- To free from dirt; to clean, to purify.
- To spiritually purify; to free from guilt or sin; to purge.