The most common and most likely answer to this crossword clue is the 9 letter word MACERATED
I've seen this crossword clue in The Guardian
M
A
C
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More clues leading to the result MACERATED
Buddy explains!

The straight part
We know that "softened by soaking" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case softened by soaking = macerated.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 MACERATED mean?
MACERATED verb- To soften (something) or separate it into pieces by soaking it in a heated or unheated liquid.
- To make lean; to cause to waste away.
- To subdue the appetite by poor or scanty diet; to mortify.
- To mortify the flesh in general.