Comers solution
by Kegler

22 Across is RISING STARS; the first letters of the extra words spell out VERTICAL UNCLUED ENTRIES ASCEND.
Accordingly, the unclued Down entries are the names of stars, entered bottom to top.

Comers solution grid

Across
1BOO + TIE {Valets}
5WAR(P)S {endless}
9SU(R)RE + A-LIST {roses}
12NUT (even letters) {terrible}
13LAIR (LIAR anag) {Incredibly}
14EIRE (rev) {cabin}
15sQUIRTS {afternoon}
18DuRESS {line}
21POLES ("POLLS" hom) {upper-class}
22RISING STARS
24AS + TRiAL {notes}
26SEAL (2 defs) {coming}
28SPARE PART (2 defs, pun) {Lacking}
30OMELET (hidden) {unusual}
31ICING ("I SING" hom) {eating}
32LA + NAI (rev) {departed}
33STEP (rev) {easily}
34OBLIGER (BIG ROLE anag) {needed}
Down
1DENEB
2OUTRE (ROUTE anag) {truck}
3T(R)EE {rabid}
4IRA + Q {invariably}
6A + L + L {Enraged}
7ALTAIR
8S + TRESS {straight}
9SIRIUS
10BETELGEUSE
11SPICA
16CASTOR
17ANTARES
19POLARIS
20SNARES (NASSER anag) {Anwar}
22RAY(ON)S {Silvery}
23ST(PET)E (SET anag) {Columnists}
25S + PILL {every}
27RIGEL
28SMUT (1st letters) {natural}
29RI(N)G {dialing}