Keep quiet about religious splinter group conversion. (6)
I believe the answer is:
secret
'keep quiet' is the definition.
'secret' can be an answer for 'quiet' (thesaurus). I'm not certain of the 'keep' bit.
'about religious splinter group conversion' is the wordplay.
I cannot quite understand how this works, but
'about' could be 're' ('re' means regarding or about) and 're' is located in the answer.
'group' could be 'sect' (I've seen this in other clues) and 'sect' is found within the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for secret that I've seen before include "Security marking" , "Clandestine, undercover" , "Hidden; unknown" , "It's not to be told" , "One not to be divulged" .)