Tree in estate, say, outside England's borders (5)
I believe the answer is:
cedar
'tree' is the definition.
(cedar is a kind of tree)
'estate say outside england's borders' is the wordplay.
'estate say' becomes 'car' (estate is a type of car).
'outside' is an insertion indicator.
'borders' suggests removing the centre (only the edge or border letters remain).
'england' with its centre taken out is 'ed'.
'car' placed around 'ed' is 'CEDAR'.
'in' is the link.
(Other definitions for cedar that I've seen before include "Tall conifer" , "Great hardwood tree associated with Lebanon" , "Tall coniferous tree" , "may have needles?" , "Raced around a great hardwood tree" .)