The most common and most likely answer to this crossword clue is the 8 letter word SPLAYING
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More clues leading to the result SPLAYING
Buddy explains!

The straight part
We know that "Spreading" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case spreading = splaying.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 SPLAYING mean?
SPLAYING verb- To spread; spread out.
- To dislocate, as a shoulder bone.
- To turn on one side; to render oblique; to slope or slant, as the side of a door, window etc.
- To rearrange (a splay tree) so that a desired element is placed at the root.
- To spay; to castrate.
- A shape or motion that splays.