The most common and most likely answer to this crossword clue is the 6 letter word DELUGE
I've seen this crossword clue in The Times
D
E
L
U
G
E
More clues leading to the result DELUGE
- Dave’s outside with toboggan in downpour
- Huge flood of water to carry in river
- Get off toboggan, perhaps, in flood
- Torrent of water from river covering lounge, oddly
- Bear trapped in river flood
- Tug overwhelmed by river in flood
- Tug sunk in river flood
- Pull into river swamp
- Bear caught in Welsh river flood
- Bear in river swamp
Buddy explains!

The straight part
We know that "downpour" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case downpour = deluge.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 DELUGE mean?
DELUGE noun- A great flood or rain.
- An overwhelming amount of something; anything that overwhelms or causes great destruction.
- (military engineering) A damage control system on navy warships which is activated by excessive temperature within the Vertical Launching System.
- To flood with water.
- To overwhelm.