Reluctant to wear Church dress (6)
I believe the answer is:
clothe
'dress' is the definition.
(I know that dress can be written as clothe)
'reluctant to wear church' is the wordplay.
'reluctant' becomes 'loth' (if you are loth to do something you are reluctant).
'to wear' is an insertion indicator (to wear something is to be covered up by it).
'church' becomes 'CE' (Church of England).
'loth' inserted inside 'ce' is 'CLOTHE'.
(Other definitions for clothe that I've seen before include "apparel" , "Attire" , "Dress (someone)" , "robe" , "Provide cover for body and limbs" .)