Properly both a member and a friend (7)
I believe the answer is:
legally
'properly both a' is the definition.
I can't judge whether this definition defines the answer.
'member and a friend' is the wordplay.
'member' becomes 'leg' (member can mean a limb).
'and' means one lot of letters go next to another.
'a friend' becomes 'ally' (an ally is a friend or supporter).
'leg'+'ally'='LEGALLY'
Can you help me to learn more?
(Other definitions for legally that I've seen before include "In a manner approved by law" , "according to the national regulations" , "As regards the law" , "without offence" , "abiding by the rules" .)