The most common and most likely answer to this crossword clue is the 5 letter word CYNIC
I've seen this crossword clue in Independent
C
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C
More clues leading to the result CYNIC
- Some fancy nice person holding sceptical views
- Like old characters in game, less than completely pleasant
- Military leader around US city backing sceptical commentator
- From fancy niche one takes a jaundiced view
- Fancy niche accommodation for sceptic
- Pessimist occasionally crying is melancholic at heart
- Sceptic close to army blocks top officer’s rise
- She doubts motives shown when niceness follows intimacy
- Pessimist‘s opposing choices adopted by commander
- A bit of diplomacy? Nice, but I doubt your motives
Buddy explains!

The straight part
We know that "She doubts motives" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case she doubts motives = cynic.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 CYNIC mean?
CYNIC noun- A person who believes that all people are motivated by selfishness.
- A person whose outlook is scornfully negative.
- Cynical (in all senses)
- Relating to the Dog Star.