Courage to get second tree (5)
I believe the answer is:
spine
'courage' is the definition.
(I've seen this in another clue)
'second tree' is the wordplay.
I cannot really see how this works, but
'second' could be 's' (common abbreviation) and 's' is found within the answer.
'tree' could be 'pine' (pine tree is a kind of tree) and 'pine' is found within the answer.
No letters remain.
This explanation may well be incorrect...
'to get' is the link.
Can you help me to learn more?
(Other definitions for spine that I've seen before include "Part of a book" , "Series of vertebrae" , "Vertebral column" , "Vertebrae, complete" , "Thorn" .)