Complete separation from exposure to sun's rays: tan finally avoided (9)
I believe the answer is:
isolation
'complete separation' is the definition.
'isolation' can be an answer for 'separation' (isolation is a kind of separation). I am not certain of the 'complete' bit.
'exposure to sun's rays tan finally avoided' is the wordplay.
I cannot really see how this works, but
'sun' could be 'sol' (Latin for 'sun') and 'sol' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'from' is the link.
Can you help me to learn more?
(Other definitions for isolation that I've seen before include "Separation - solitude" , "Staff in such a hospital working with" , "Cutting off" , "State of separation, closing off" , "Remote and lonely state" .)