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

The straight part
We know that "of stuff transported in deluge" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case of stuff transported in deluge = alluvial.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 ALLUVIAL mean?
ALLUVIAL noun- A deposition of sediment over a long period of time by a river; an alluvial layer.
- Alluvial soil; specifically, in Australia, gold-bearing alluvial soil.
- Pertaining to the soil deposited by a stream.