Long evergreen tree (4)
I believe the answer is:
pine
I believe this is a double definition.
'long' is the first definition.
('pine' can be a synonym of 'long')
'evergreen tree' is the second definition.
(I've seen this before)
(Other definitions for pine that I've seen before include "Long - tree" , "Tree, waste away" , "Kind of needle" , "Scots fir" , "Thirst" .)