I thought I'd try my hand at creating a Laddergram, a format of puzzle I've seen in Dell's Pencil Puzzles and Word Games. The rules here are: on each row, there are three words given by clues. The second word will be an anagram of the first word minus one letter, and the third word will be an anagram of the second word minus one letter. You then record the removed letters to either side of the row, and if you do things correctly, at the end the side columns will read out a secret phrase.

As for the words, they will all be at least three letters long (therefore, for example, the first word on each row must be at least five letters long).

(Also note that, as opposed to the original format, in this one occasionally the word might be a proper noun, an abbreviation, or a specific foreign word - though usually it won't be.)

Example: | P | APPLE | PALE | LAP | E |

Now for the actual puzzle:

------------------------------------------------
|   | 1          | 2          | 3          |   |
------------------------------------------------
|   | 4          | 5          | 6          |   |
------------------------------------------------
|   | 7          | 8          | 9          |   |
------------------------------------------------
|   | 10         | 11         | 12         |   |
------------------------------------------------
|   | 13         | 14         | 15         |   |
------------------------------------------------
|   | 16         | 17         | 18         |   |
------------------------------------------------
|   | 19         | 20         | 21         |   |
------------------------------------------------

1. Cosmic streaker
2. Middle of Malory's title?
3. Mechanical means
4. Samurai master
5. Soft murmur
6. Grown-up fairy tale characters?
7. Presents
8. Sign of anger
9. Fulfill purpose of a cathedral?
10. Hesitate
11. Chasing
12. Evaluate
13. Arctic denizen
14. Gaggle of officers
15. Crank
16. Idol?
17. Rule
18. Old-timey whirlpool
19. Horde lords
20. Put in a pocket
21. Let me be explicit: I didn't recv. it

Another hint on 21 (in addition to the hint that ffao posted in a comment):

Chr. nr. 21, to a PC

• If you're editing the puzzle, there's no reason to keep around the old, incorrect clues. It just makes things more confusing. They can always be seen in the edit history if needed. Apr 10 '18 at 21:17
• They have already edited their answer to reflect the new clues as well. Apr 11 '18 at 15:17

So, so close... Great puzzle.

1 - 2 - 3

E| METEOR | MORTE | ROTE | M

4 - 5 - 6

N| SHOGUN | SOUGH | HOGS | U

7 - 8 - 9

G| GIFTS | FIST | SIT | F

10 - 11 - 12

L| FALTER | AFTER | RATE | F

13 - 14 - 15

I| INUIT | UNIT | NUT | I

16 - 17 - 18

S| SINGER | REIGN | GIRE | N

19 - 20 - 21

H| KHANS | SANK | ??? | S

English Muffins

4 - 5 - 6

| N | SHOGUN | SOUGH | HOGS | U |

7 - 8 - 9

| G | GIFTS | FIST | ??? | F |

10 - 11 - 12

| L | FALTER | AFTER | RATE | F |

And even though I don't have all the rungs, the full answer is

ENGLISH MUFFINS

• I'm so sorry, I just realized I messed up on 7-8-9. It looks like I'll have to come up with a new set of clues and edit... Anyway, your answers for 7-8-9 were correct, it was totally my mistake. Apr 10 '18 at 21:03
• @DanielSchepler No worries. It's a fun puzzle, I don't mind solving one more rung.
– user27014
Apr 10 '18 at 21:09

OK, since nobody seems to want to just come out and say the last answer, let me post it so I can mark the question as solved:

21:

NAK