Bristlecone pine, for example (4)
I believe the answer is:
tree
'bristlecone pine for example' is the definition.
(bristlecone pine is a kind of tree)
This is all the clue.
(Other definitions for tree that I've seen before include "Box or bay maybe?" , "Eg, laburnum" , "Plane, e.g." , "Plane or pine, for example?" , "''I think that I shall never see / A poem lovely as a ...'' (Kilmer)" .)