I'm involved in devout little sermon (6)
I believe the answer is:
homily
'sermon' is the definition.
(homily is a kind of sermon)
'i'm involved in devout little' is the wordplay.
'involved' indicates an anagram (involved can mean confusing or complex).
'in' indicates putting letters inside.
'devout little' becomes 'holy' (I am not sure about this - if you are sure you should believe this answer much more).
'im' is an anagram of 'mi'.
'mi' placed inside 'holy' is 'HOMILY'.
Can you help me to learn more?
(Other definitions for homily that I've seen before include "Sermon on a moral issue" , "Address" , "Lecture on a moral topic" , "Edifying discourse" , "Sermon on a religious topic" .)