Mode of singing in wedding involving soprano (6)

I believe the answer is:
unison
'mode of singing' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'wedding involving soprano' is the wordplay.
'wedding' becomes 'union' (I've seen this in another clue).
'involving' indicates putting letters inside.
'soprano' becomes 's' (musical abbreviation).
'union' placed around 's' is 'UNISON'.
'in' is the link.
Can you help me to learn more?
(Other definitions for unison that I've seen before include "The concordant trade union?" , "Musical agreement" , "All voices together" , "Simultaneous utterance" , "Harmony - public services' trade union" .)
