Trim a conifer (6)
I believe the answer is:
spruce
I believe this is a double definition.
'trim' is the first definition.
(synonyms)
'a conifer' is the second definition.
(I know that spruce is a type of conifer)
(Other definitions for spruce that I've seen before include "Coniferous tree" , "tree with needle-like leaves" , "Evergreen pyramid-shaped tree" , "Smart-looking sort of fir tree" , "thing for fairy to be on top of?" .)