The most common and most likely answer to this crossword clue is the 8 letter word FRACTION
I've seen this crossword clue in The Guardian
F
R
A
C
T
I
O
N
More clues leading to the result FRACTION
- Party hosts ending on floor, one over the eight perhaps?
- It might be proper, right to infiltrate political group
- Perhaps half of Republicans originally in dissenting group
- Part supporting heartless undertaking
- A bit of fighting on Friday
- Perhaps one over six feet ten keeps reversing car with strain ultimately
- Small part of French operation
- Rule accepted by party – it may be improper
- Subsection of right infiltrating activist group
- A number may be vulgar about right wing
Buddy explains!

The straight part
We know that "Part" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case part = fraction.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 FRACTION mean?
FRACTION noun- A part of a whole, especially a comparatively small part.
- A ratio of two numbers, the numerator and the denominator, usually written one above the other and separated by a horizontal bar.
- A component of a mixture, separated by fractionation.
- In a eucharistic service, the breaking of the host.
- A small amount.
- The act of breaking, or state of being broken, especially by violence.
- To divide or break into fractions.