As extracted from yeast, even today! (3)
I believe the answer is:
yet
'even today' is the definition.
'yet' can be an answer for 'even' (I've seen this in another clue). I am unsure of the 'today' bit.
'as extracted from yeast' is the wordplay.
'extracted from' is a deletion indicator.
'yeast' with 'as' removed is 'YET'.
Can you help me to learn more?
(Other definitions for yet that I've seen before include "Up to the present time" , "To this time, nevertheless" , "Thus far" , "Although" , "'But, however (3)'" .)