There are four entries that refer the four classic elements. EARTH
FIRST ELEMENT; dug up[-----]
SECOND ELEMENT; at this present time, according to Chaucer[-----]
THIRD ELEMENT; hinderance[---]
; and FIRE
FOURTH ELEMENT; Nov. 5 in Britain[----]
. Each such entry has as secondary clue that refers to a word of phrase that is formed by the three entries in that line: unEARTHed; noW AT
ERst; impAIRment; and bonFIRE night.
In this meta, what the clue "Disease prevention by DNA modification" has been[-------]
refers to a "removed clue". And quintessence and quintessential derive from and literally mean, the concept of a "Fifth Element".
So..... The removed clue that is not included in this grid would be: FIFTH ELEMENT; Disease prevention by DNA modification. And there'd be a row of entries that along with the name of the fifth element would answer the clue "Disease prevention by DNA modification".
In the center row we have entries GEN
Flowers involved in a sex scandal that actually helped the political candidate. (Now that's a clue taylored for the ---- Xer's)[---]
Real rate of return (taking compound interest into account) abbr.[---]
with a row of five blank spaces. If we insert the name of the Fifth Element into it we get:
ETHER (or Aether) is the fifth element in classical Greek philosophy and therefore the answer to the meta.