Small pine, possibly, or spruce (7)
I believe the answer is:
smarten
'spruce' is the definition.
(I've seen this in another clue)
'small pine possibly' is the wordplay.
I cannot quite understand how this works, but
'small' could be 'sm' and 'sm' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'or' acts as a link.
Can you help me to learn more?
(Other definitions for smarten that I've seen before include "Improve appearance" , "Brighten (up)" , "Spruce up" , "Become bright, tidy and more efficient" .)