Pious Oscar wrapped in shabby duvet (6)
I believe the answer is:
devout
'pious' is the definition.
(synonyms)
'oscar wrapped in shabby duvet' is the wordplay.
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'wrapped in' indicates putting letters inside.
'shabby' is an anagram indicator.
'duvet' with letters rearranged gives 'devut'.
'o' placed into 'devut' is 'DEVOUT'.
(Other definitions for devout that I've seen before include "Showing religious commitment" , "Pious, given to prayer" , "Pious and worshipful" , "Earnestly religious, prayerful" , "God-fearing" .)