Crossword Help Forum
Forum Rules

23a.Omitting vowel e almost noisily in retreat.
e-i-i-n, elision ?
20d. Brain particle made of protein, not the margins, prion ?
Its the last corner of the damn thing

Elision and Prion - both correct

Prion is an anagram of Protein without the margins of "the" (that is, without the 't' and the 'e')

Elision is almost a reversal of noisily, plus E

23a.
E + ,almost noisily in retreat = E(y)lision
20d.
the margins = T(h)E
anagram of protein minus t,e.

first one is elision..it means omission of a vowel

Thank you all for the information