Courage to get small tree (5)
I believe the answer is:
spine
'courage' is the definition.
(I've seen this in another clue)
'small tree' is the wordplay.
I cannot really see how this works, but
'small' could be 's' (abbreviation - e.g. clothes size) and 's' is located in the answer.
'tree' could be 'pine' (pine tree is a kind of tree) and 'pine' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'to get' is the link.
Can you help me to learn more?
(Other definitions for spine that I've seen before include "Part of book's jacket" , "Part of a book" , "Backbone" , "Series of vertebrae" , "Vertebral column" .)