For speaking out, dissenting voice is called before the union (3)
I believe the answer is:
nee
'called before the union' is the definition.
I can't judge whether this definition defines the answer.
'for speaking out dissenting voice' is the wordplay.
'for speaking out' shows a homophone (sound like).
'dissenting voice' becomes 'nay' (I've seen this in another clue).
'nay' sounds like 'NEE'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for nee that I've seen before include "Prefix indicating maiden name of married woman" , "indicate old name" , "Indicates the maiden name of a married woman" , "Surnamed at birth" , "Born as (former name)" .)