Dodgy religious group includes peculiar aspect (7)
I believe the answer is:
suspect
'dodgy' is the definition.
(I've seen this before)
'religious group includes peculiar aspect' is the wordplay.
'religious group' becomes 'sect' (I've seen this before).
'includes' means one lot of letters goes inside another.
'peculiar aspect' becomes 'usp' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'sect' placed around 'usp' is 'SUSPECT'.
Can you help me to learn more?
(Other definitions for suspect that I've seen before include "one on bail, perhaps" , "Distrust, have doubts about" , "smell a rat produces" , "Doubt truth of" , "Doubt; mistrust" .)