Oak or maple (4)
I believe the answer is:
tree
I believe this clue is a double definition.
'oak' is the first definition.
(I've seen this in another clue)
'maple' is the second definition.
(maple is a type of tree)
(Other definitions for tree that I've seen before include "Elder, possibly" , "Stand for mugs" , "Large shrub with branches" , "Plane, e.g." , "Large, woody perennial plant" .)