Family tree -- those keeping it upright? (5)
I believe the answer is:
roots
This clue is a double definition.
'family' is the first definition.
(back to my roots)
'tree those keeping it upright?' is the second definition.
(Other definitions for roots that I've seen before include "Radicals" , "background" , "Underground parts of a plant" , "Cultural origins" , "a Wesker play" .)