Oak or linden (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)
'linden' is the second definition.
(thesaurus)
(Other definitions for tree that I've seen before include "Holly, perhaps" , "Beech, for example" , "Care for shoes" , "embraced by environmentalist?" , "Eg, a baobab" .)