Bush with sharp spines: son's lost much blood (4)
I believe the answer is:
gore
'blood' is the definition.
(gore means blood or violence)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for gore that I've seen before include "Blood; stab with tusk" , "piece of material" , "Impale" , "stuff from part of Kensington" , "Pierce with horn - blood" .)