Think American pressure is splitting religious group (7)
I believe the answer is:
suspect
'think' is the definition.
(suspecting is a kind of thinking)
'american pressure is splitting religious group' is the wordplay.
'american' becomes 'us'.
'pressure' becomes 'p' (abbreviation).
'is splitting' indicates putting letters inside.
'religious group' becomes 'sect' (I've seen this before).
'us'+'p'='usp'
'usp' put within 'sect' is 'SUSPECT'.
(Other definitions for suspect that I've seen before include "Hazard a guess" , "one on bail, perhaps" , "Believe to be guilty, but without proof" , "Doubt; mistrust" , "Imagine to be guilty" .)