A family member managed after midnight (4)
I believe the answer is:
gran
'a family member' is the definition.
(short for grandmother)
'managed after midnight' is the wordplay.
'managed' becomes 'ran' (both can mean organised or was in charge of).
'after' is a charade indicator (letters next to each other).
'midnight' becomes 'g' (the middle letter in 'night').
'ran' put after 'g' is 'GRAN'.
(Other definitions for gran that I've seen before include "Relation" , "She's of an older generation, in short" , "... Canaria in the Atlantic Ocean" , "Relative (colloq.)" , "Mum's mum" .)