Help Please

[johnT]

Help please
Two clues I think I've solved but can't understand logic.
19a. Beasts hold back short grey element (6) O?Y?E?
I have ORYXES and E affects first letter of 20d (I believe OS is derived from element Osmium and oryx is a beast)

20d. One after another (6) E?E?E?N
First letter E dependent on 19a being correct
I have ELEVEN but can't understand why or the logic of the clue

Thanks

[MargoTester]

Oxygen

[Captain2]

One= 1 and then another one = 1, so you have 11 (eleven)

[emeritus]

20 1 followed by another 1 = Eleven

[dannyk13]

Oxygen- g(re)y reversed inside Oxen(beasts)
Eleven written as 11 is one after another

[Lie-in King]

19d Oxygen (element) - 'oxen' (hold) 'g(re)y' (back)
20d Eleven - 11 - 1 after another (1)

[MargoTester]

Ox yg en

[johnT]

Thank you all I'll change Oryxes to Oxygen (but use of the word beasts put me onto Oryxes)

[hc4361]

Oxen are beasts :)