MUDD kicks off the week…
A solid and enjoyable puzzle. I'm a bit unsure as to my parsing of 19d though.
Thanks MUDD!

ACROSS
1. Avoidance of responsibility when policeman dismissed (3-3)
COP-OUT
COP (policeman) + OUT (dismissed)
4. Monster heading for warren acting like rabbit? (8)
WHOPPING
W[arren] (heading for) + HOPPING (acting like rabbit)
9. Little time required in new role, I wait (6)
LOITER
T (little time) required in (ROLE I)* (*new)
10. Doctor I recall touring southern English city (8)
CARLISLE
(I RECALL)* (*doctor) touring S (southern)
12. Dollars exciting potential killer (8)
BUCKSHOT
BUCKS (dollars) + HOT (exciting)
13. Island tracks on the radio? (6)
RHODES
"roads" = RHODES (tracks, "on the radio")
15. Reviewed in March, social club (4)
COSH
([marc]H SOC[ial] (in))< (<reviewed)
16. Ship on sea sailing west around northern country (7)
DENMARK
ARK (ship) on ((MED)< (sea, <sailing west) around N (northern))
20. Provoke smoker? (7)
INCENSE
Double (cryptic) definition
21. Weapon in ten pieces, every second part needed (4)
EPEE
[t]E[n] P[i]E[c]E[s] (every second part needed)
25. OK if a try converted (6)
RATIFY
26. Referencing a passage, first of chords on clavier played (8)
CERVICAL
C[hords] (first of) on (CLAVIER)* (*played)
28. Sparkling return of Sicilian hothead, young girl (8)
DIAMANTE
(ETNA (Sicilian hothead) + MAID (young girl))
29. Rolls and Royce, for example, in opera? (6)
CARMEN
CAR MEN (Rolls and Royce, for example)
30. Tough year with the wound on front of leg (8)
LEATHERY
(YEAR with THE)* (*wound) on L[eg] (front of)
31. Article in eye, more sinewy (6)
LEANER
AN (article) in LEER (eye)
DOWN
1. Steering away from the other bicycle, a drunk (8)
CELIBACY
2. Jam sandwiches in Cellophane originally for royal (8)
PRINCESS
PRESS (jam) sandwiches (IN + C[elophane] (originally))
3. Tense — and hard, it’s inferred? (6)
UNEASY
Double (cryptic) definition
5. Burner entering the atmosphere (4)
HEAT
[t]HE AT[mosphere] (entering)
6. Fish, couple reeled up, frozen! (8)
PILCHARD
(CLIP)< (couple, <reeled up) + HARD (frozen)
7. Current faction under lock and key (6)
INSIDE
IN (current) + SIDE (faction)
8. Engineer agrees that might help things run smoothly (6)
GREASE
11. Nevertheless, we dipped into float (7)
HOWEVER
WE dipped into HOVER (float)
14. One attempting overhead shot, a beauty (7)
SMASHER
17. Where lightning comes out of the blue (2,1,5)
IN A FLASH
18. Small bowler for someone with enormous helmet? (8)
SPACEMAN
S (small) + PACEMAN (bowler, cricket)
19. German bitter about rule, number finally turning up (8)
BERLINER
BEER (bitter) about (R (rule) + (NIL)< (number, <finally turning up))
22. Party upset about free marriage (6)
BRIDAL
(LAB)< (party, <upset) about RID (free)
23. Layers in tart as mushy (6)
STRATA
24. Fly entering cocoa via teaspoon (6)
AVIATE
[coco]A VIA TE[aspoon] (entering)
27. Dwarf, for example, big name! (4)
STAR
Double (cryptic) definition
Mudd was in sparkling form today like a 28 (DIAMANTE)!
There was plenty to smile at besides the aforementioned sparkler: WHOPPING, LEATHERY, RATIFY (such a neat surface) and GREASE but top marks go to CELIBACY for its definition and surface.
Thanks to Mudd and Teacow (that’s how I parsed 19d).
I think 19 down is beer (bitter) about line (rule) r (number finally)
I thought that Tilloubill@2 but it gives an extra “e”. If this were the Grauniad I’d say it was an editing error, as they are common there but it is that or the somewhat unsatisfactory parsing given by Teacow (which I also settled on) which does not really justify “finally” and has “R” for “rule” which is not in my (ancient) Chambers.
Other than that, delightful Monday fare. Took me a while to see why “clip” was “couple” (as in “join together”) and “pilchard” I recently learned is the same thing as a sardine, though “sardine” is sometimes used for smaller individuals. Been eating both all my life and only just discovered what they are!
Many thanks Teacow and Mudd.
Thanks Mudd and Teacow. I had the same difficulties as others over 19dn, but I can confirm that Chambers 2016 p 1283 has “r or r. abbrev … rule (law).”
I’m in agreement with Diane @1 that CELIBACY deserves top marks and also in nominating WHOPPING and RATIFY.
Somewhat less impressed by two hiddens in the Down clues both indicated by ‘entering’. 1) it’s preferable to see a lack of repetition with indicators and 2) shouldn’t a hidden instruction suggest the word is already there? ‘Entering’ is an insertion indicator more than a hidden.
Thanks Mudd and Teacow
I was expecting the clue for BRIDAL would yield a noun.
Club/cosh was unfamiliar — Collins says it’s British.
Good puzzle/blog. Liked celibacy and grease, agree Berliner a bit off.
Btw doesn’t Berliner mean donut rather than German, leading to much local hilarity when the saintly JFK announced ‘ich bin ein Berliner’ in attempted solidarity?
James P @8: A little bit of urban myth there I am afraid – but also, without the indefinite article, there is no problem. In German the article is omitted before professions/origins (so I might say “Ich bin Lehrer” for “I am a teacher” or “Ich bin Berliner” so just “Berliner” on its own can be either a pastry or a person from Berlin.
GDU@6: Again I learn a word I have known for over 50 years turns out not to be there in other forms of English. Thank you. I too was thrown by “bridal” for “marriage”. The closest I could come (which may not be close enough) was that “marriage” might be used as an adjective as in “marriage suite” or “her marriage clothes” though I agree both sound rather odd.