Important question and answer session, finally, with corporation (7)
I believe the answer is:
quantum
'important question' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'answer session finally with corporation' is the wordplay.
'answer session finally' becomes 'quan' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'with' is a charade indicator (letters next to each other).
'corporation' becomes 'tum' ('corporation' can humorously mean belly fat).
'quan'+'tum'='QUANTUM'
'and' is the link.
Can you help me to learn more?
(Other definitions for quantum that I've seen before include "Type of mechanics, jump or leap" , "Amount - measure" , "One giant leap for mankind" , "Smallest possible amount (eg of energy) - large and sudden" , "Tiny energy packet" .)