The most common and most likely answer to this crossword clue is the 9 letter word SQUELCHED
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Buddy explains!

The straight part
We know that "subdued" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case subdued = squelched.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 SQUELCHED mean?
SQUELCHED verb- To halt, stop, eliminate, stamp out, or put down, often suddenly or by force
- (radio technology) to suppress the unwanted hiss or static between received transmissions by adjusting a threshold level for signal strength, below which the signal is suppressed by applying a gain of zero, and above which a positive (and linear from zero) gain is applied.
- To make a sucking, splashing noise as when walking on muddy ground
- To walk or step through a substance such as mud
- Having been squelched.