Salvation Army doctrine mainly dedicated to religious use (6)
I believe the answer is:
sacred
'dedicated to religious use' is the definition.
I can't judge whether this definition defines the answer.
'salvation army doctrine mainly' is the wordplay.
'salvation army' becomes 'SA' (abbreviation).
'doctrine' becomes 'credo' (credo is a kind of doctrine).
'mainly' means to remove the last letter (virtually or mainly the word, but not all of it).
'credo' with its last letter removed is 'cred'.
'sa'+'cred'='SACRED'
Can you help me to learn more?
(Other definitions for sacred that I've seen before include "Sanctified" , "not to be interfered with?" , "Hallowed, consecrated" , "'Consecrated, holy (6)'" , "Holy, blessed" .)