Member with independent opinion (4)
I believe the answer is:
mind
'opinion' is the definition.
(mind is a kind of opinion)
'member with independent' is the wordplay.
'member' becomes 'm'.
'with' means one lot of letters go next to another.
'independent' becomes 'ind' (I've seen this in other clues).
'm'+'ind'='MIND'
(Other definitions for mind that I've seen before include "Intellect; object to" , "Take care of; intellect" , "Seat of the faculty of reason" , "Look after" , "Brain" .)