Under arrest, suspect’s initial concerns (13)

I believe the answer is:

apprehensions

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'concerns' is the definition.
The answer and definition can be both related to thinking as well as being plural nouns.
Perhaps they are linked in a way I don't understand?

'under arrest suspect's initial' is the wordplay.
'under' says to put letters next to each other.
'arrest' becomes 'apprehension' (synonyms).
'suspect's initial' becomes 's' (I can't explain this - if you can you should believe this answer much more).
'apprehension'+'s' is 'APPREHENSIONS'.

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I've seen this clue in The Sunday Times.

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