Ancestor's tree (5)
I believe the answer is:
elder
I believe this is a double definition.
'ancestor's' is the first definition.
(I've seen this before)
'tree' is the second definition.
(elder is a kind of tree)
(Other definitions for elder that I've seen before include "Senior member - plant" , "Berry-bearing shrub" , "Older person - one's senior" , "Character of church" , "Tree; of greater age" .)