Oak or willow (4)
I believe the answer is:
tree
This clue is a double definition.
'oak' is the first definition.
(I've seen this before)
'willow' is the second definition.
(thesaurus)
(Other definitions for tree that I've seen before include "Genealogy chart" , "Eg, a baobab" , "Large plant with trunk" , "Older actor" , "elder, maybe" .)