A Puzzle By Radler

[Matakari]

http://crypticcrosswords.net/puzzles/monthly-prize-puzzles/mpp-117/

Good evening, completed the Sunday Times and Mephisto Crosswords and learned much from the answers given, many of which appeared to be quite abstruse especially for Mephisto. I’m still studying many of them. There were quite a few anagrams that were pretty easy to spot, however.

For another learning experience, I am seeking answers for the following from:
A Puzzle by Radler

The clues to six thematic answers lack a definition. Symbolically, they could represent one of the other answers. What is it?

ACROSS:
1 Brown envelopes left: is old lady supplying protection? (8) : ??T?S?A?
9 Put information on counter or cover with plate (8) : ??E?O?E?
14 Runs off to tell and make proud (5) : ??A?E ( ELATE )
23 Possible to identify South Island in fantastic epic myth (11) : ??E????????

DOWN:
1 Speech delivered then clears up (8) : ????S???
6 Every spring tip of shoots grows on trees (7) : ??O?N?S
7 Weapons cart will be dry under covers (9) : ??T???E?Y
11 Charlie’s ironic, ruthlessly limiting new music, cutting off service (12) : ?I?C?M??????
20 Guide for future display of colours (7) : R??????

[scorpiojo]

14 (r - runs) elate

[Neveracrossword]

7 Artillery, weapons - from c ART w ILL bE dRY (ignore the first letter, cover)

[Mamyalynne]

20 Rainbow

https://www.girlguiding.org.uk/what-we-do/rainbows-5-7/

[Neveracrossword]

1 Talisman, protection. Tan, brown, with is Is Ma, old lady, inside.

[ProfessorMaisie]

9 NITROGEN (thematic)
23 SPECIFIABLE
1d TUNGSTEN (thematic)
6 ABOUNDS
11 CIRCUMCISION

[cashier]

11 Circumcision?

[Matakari]

Many thanks, ProfessorMaisie, NACW, Scorpiojo, Mamyalynne, Cashier ! I'm almost there now!

[MacSNaP]

Tungsten (W),
Oxygen (O),
Nitrogen (N),
iodine (der???),
Boron (B),
Radium (Ra)

Anyone see why Iodine might be 'Der' to read wonderbra.

Cannot get 15D (A-E---D-R), nor 22A (A--).

[Neveracrossword]

Maybe Matakari will be able to help....

[MacSNaP]

(Ra)(I)(N)(B)(O)(W)

[ProfessorMaisie]

22a def 'I've got it' = AHA (palindromic answer - 'both ways')
15d ALEXANDER ( ALE + X = 'cross' 'with' = AND + ER 'Queen')