It's in our blood, being against the corporation (8)
I believe the answer is:
antibody
'it's in our blood' is the definition.
I can't tell whether this defines the answer.
'against the corporation' is the wordplay.
'against' becomes 'anti' (prefix meaning against).
'the corporation' becomes 'body' (I can't explain this - if you can you should give a lot more credence to this answer).
'anti'+'body'='ANTIBODY'
'being' is the link.
Can you help me to learn more?
(Other definitions for antibody that I've seen before include "Antigen attacker" , "Protective protein in blood which destroys inimical substances" , "personal protection" , "protection against disease" , "Immune system protein" .)