Trim tree (6)
I believe the answer is:
spruce
I believe this is a double definition.
'trim' is the first definition.
(synonyms)
'tree' is the second definition.
(spruce is a kind of tree)
(Other definitions for spruce that I've seen before include "tree with needle-like leaves" , "Coniferous tree" , "Neat and smart like pine tree" , "Evergreen pyramid-shaped tree" , "Neat and tidy like tree" .)