Surmise religious group will accept us provisionally at first (7)
I believe the answer is:
suspect
'surmise' is the definition.
(I know that surmise can be written as suspect)
'religious group will accept us provisionally at first' is the wordplay.
'religious group' becomes 'sect' (eg a religious sect).
'will accept' indicates putting letters inside.
'at first' says to take the initial letters.
The first letter of 'provisionally' is 'p'.
'us'+'p'='usp'
'sect' enclosing 'usp' is 'SUSPECT'.
(Other definitions for suspect that I've seen before include "Doubt - man held by police" , "Imagine to be guilty" , "One is believed to be guilty but without proof" , "Have qualms about" , "Funny" .)