To avoid risk, appropriate one's back should be well protected! (8)
I believe the answer is:
hedgehog
'one's back should be well protected' is the definition.
I can't judge whether this definition defines the answer.
'to avoid risk appropriate' is the wordplay.
I cannot quite see how this works, but
'avoid' could be 'hedge' (hedging is a kind of avoiding) and 'hedge' is located in the answer.
'appropriate' could be 'hog' (both can mean to take for oneself) and 'hog' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for hedgehog that I've seen before include "Nocturnal mammal" , "Prickly rodent" , "Prickly mammal" , "one is far from spineless" , "Prickly beast" .)