Reportedly, a family member, is against it (4)
I believe the answer is:
anti
'against it' is the definition.
I can't tell whether this defines the answer.
'reportedly a family member' is the wordplay.
'reportedly' indicates a 'sounds like' (homophone) clue.
'a family member' becomes 'auntie' (I've seen this before).
'auntie' is a homophone of 'ANTI'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for anti that I've seen before include "[NO MAN]" , "one opposing?" , "Against, informally" , "Someone opposed (to a policy?)" , "Adversary" .)