Family tree reveals this down-to-earth approach? (7)
I believe the answer is:
descent
'family tree' is the definition.
(I know that descent is a type of family tree)
'this down-to-earth approach?' is the wordplay.
'this down' becomes 'd'.
'to earth' becomes 'E'.
'approach?' becomes 'scent' (I can't justify this - if you can you should give a lot more credence to this answer).
'd'+'e'+'scent'='DESCENT'
'reveals' acts as a link.
Can you help me to learn more?
(Other definitions for descent that I've seen before include "that concerns genealogist?" , "Lineage" , "Drop" , "Downward journey" , "Coming down" .)