Marriage restraint, reportedly? (6)
I believe the answer is:
bridal
'marriage' is the definition.
(I know that bridal is a type of marriage)
'restraint reportedly?' is the wordplay.
'restraint' becomes 'bridle' (bridle is a kind of restraint).
'reportedly?' indicates a 'sounds like' (homophone) clue (I've seen 'reportedly' mean this).
'bridle' is a homophone of 'BRIDAL'.
(Other definitions for bridal that I've seen before include "Woman in White" , "of marriage" , "Nuptial" , "To do with wedding - perhaps a suite" , "of the train puller?" .)