The most common and most likely answer to this crossword clue is the 7 letter word SUSPECT
I've seen this crossword clue in The Guardian
S
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P
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More clues leading to the result SUSPECT
- Dodgy American pastor's leader in religious group
- Doubt South American kissed briefly, as you say
- Dodgy American originally performing in group touring clubs
- South American with muscle finally caught wanted man
- Have doubts about group protecting American leader in Paris
- Half the people looking to catch us have a sneaking feeling
- Dodgy religious group includes peculiar aspect
- Cult adopting unique selling point is dubious
- Questionable cult defends American power
- Dodgy American parking in camp
Buddy explains!

The straight part
We know that "Questionable" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case questionable = suspect.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 SUSPECT mean?
SUSPECT noun- A person who is suspected of something, in particular of committing a crime.
- To imagine or suppose (something) to be true, or to exist, without proof.
- To distrust or have doubts about (something or someone).
- To believe (someone) to be guilty.
- To have suspicion.
- To look up to; to respect.
- Viewed with suspicion; suspected.
- Viewing with suspicion; suspecting.