Taking on commercial financial derivative (8)
I believe the answer is:
adoption
'taking on' is the definition.
(I've seen this before)
'commercial financial derivative' is the wordplay.
'commercial' becomes 'ad' (abbreviation for advertisement).
'financial derivative' becomes 'option' (I can't justify this - if you can you should believe this answer much more).
'ad'+'option'='ADOPTION'
Can you help me to learn more?
(Other definitions for adoption that I've seen before include "how to create a family" , "Act of taking as one's own" , "process to select candidate" , "formal selection of candidate?" , "The taking on of someone else's child" .)