The most common and most likely answer to this crossword clue is the 7 letter word DRIPPED
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More clues leading to the result DRIPPED
Buddy explains!

The straight part
We know that "came down gradually" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case came down gradually = dripped.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 DRIPPED mean?
DRIPPED verb- To fall one drop at a time.
- To leak slowly.
- To let fall in drops.
- (usually with with) To have a superabundance of valuable things.
- (of the weather) To rain lightly.
- To be wet, to be soaked.
- To whine or complain consistently; to grumble.