Mother or father (6)
I believe the answer is:
parent
I believe this clue is a double definition.
'mother' is the first definition.
(I've seen this in other clues)
'father' is the second definition.
(I know that father is a type of biological parent)
(Other definitions for parent that I've seen before include "Mum or dad" , "What mums and dads do" , "Procreator" , "Mother or father or what they do" , "Author" .)