The most common and most likely answer to this crossword clue is the 9 letter word FAITHLESS
I've seen this crossword clue in The Guardian
F
A
I
T
H
L
E
S
S
More clues leading to the result FAITHLESS
Buddy explains!
The straight part
We know that "Disloyal/when trust is diminished" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case disloyal/when trust is diminished = faithless.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 FAITHLESS mean?
FAITHLESS adjective- Lacking faith; lacking belief in something.
- Not believing in God, religion, or a comparable ideology.
- Unfaithful (said of people, towards their partners)
- Not observant of promises or covenants.
- Not true to allegiance, duty, or vows
- Serving to disappoint or deceive