Speaker's parentage in dispute (7)
I believe the answer is:
dissent
'dispute' is the definition.
(I've seen this before)
'speaker's parentage' is the wordplay.
'speaker's' shows a homophone (sound like).
'parentage' becomes 'descent' (synonyms).
'descent' is a homophone of 'DISSENT'.
'in' is the link.
(Other definitions for dissent that I've seen before include "Opposition" , "Raise objections" , "Differ" , "Withhold approval" , "Protest" .)