Any bit treated has too much blood protein (8)
I believe the answer is:
antibody
'blood protein' is the definition.
'antibody' can be an answer for 'protein' (antibody is a kind of protein). I am not sure about the 'blood' bit.
'any bit treated has too much' is the wordplay.
'treated' indicates an anagram.
'has' indicates putting letters inside.
'too much' becomes 'od' (abbreviation for overdose).
'any'+'bit'='anybit'
'anybit' with letters rearranged gives 'antiby'.
'antiby' enclosing 'od' is 'ANTIBODY'.
Can you help me to learn more?
(Other definitions for antibody that I've seen before include "Pathogen fighter" , "Fighter in blood" , "personal protection" , "Protective protein in blood which destroys inimical substances" , "Protein produced in the blood" .)