Cannon part soldier finally found in tree (6)
I believe the answer is:
breech
'cannon part' is the definition.
(I've seen this in another clue)
'finally found in tree' is the wordplay.
'finally found' becomes 'r' (I am not sure about this - if you are sure you should believe this answer much more).
'in' means one lot of letters goes inside another.
'tree' becomes 'beech' (beech tree is a kind of tree).
'r' going into 'beech' is 'BREECH'.
'soldier' acts as a link.
Can you help me to learn more?
(Other definitions for breech that I've seen before include "Rear part of rifle" , "Back end of a gun barrel" , "(Half of) lower garment" , "Back part of a gun barrel" , "Back part of rifle" .)