First woman to introduce 50 percent-volume progress (6)
I believe the answer is:
evolve
'progress' is the definition.
(I've seen this in another clue)
'first woman to introduce 50 percent-volume' is the wordplay.
'first woman' becomes 'Eve' (first woman in the bible).
'to introduce' is an insertion indicator (to introduce to can mean to insert or include).
'50 percent volume' becomes 'vol' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'eve' placed around 'vol' is 'EVOLVE'.
Can you help me to learn more?
(Other definitions for evolve that I've seen before include "Grow slowly" , "Develop or change very gradually (6)" , "Gradually acquire new characteristics" , "Reveal a secret" , "Change gradually to present condition" .)