Honestly RM is a little hit-and-miss for me. Some clues are beautiful, but others just feel clumsy. It also consistently seems like anagram indicators are unconventional or just missed, same with removals. Minor gripes aside, fairly straightforward.

For 11A and 14D, The Clue Clinic lists "up" as an "advanced" indicator. Otherwise I think it would be parsed as an &lit that doesn't quite work.

3D doesn't quite work for me either: ENVY is a noun but JEALOUS is an adjective. And 26D's use of FU feels like a little bit of a stretch.

Across

1

Watch lead builder put in a beam (6)
TIMBER — TIMER (watch) with B (lead builder) inside

4

Shunned directions and used teeth (8)
ESCHEWED — ES (directions) and CHEWED (used teeth)

10

Distasteful but sweet? (9)
UNSAVOURY — double def.

11

Grown-up is mistaken (5)
WRONG — anagram (up) of GROWN

12

Sit around, light-headed, on the fine sand (4)
SILT — SIT around L (first letter of light)

13

Jester operates without set pieces like The Mikado (5,5)
COMIC OPERA — COMIC (jester) then OPERAtes without set

15

Quite an ugly old thing (7)
ANTIQUE — anagram (ugly) of QUITE AN

16

Did Ron go without Di? Dill! (6)
DRONGO — diDRONGO without di

19

Insist that fellow wear even less dreads (6)
DEMAND — MAN (fellow) inside (wear) DED (odd letters, "even less", of dreads)

21

Travel with some Europeans or pay for yourself (2,5)
GO DUTCH — GO (travel) with DUTCH (some Europeans)

23

Where protesters gather for a nice kip and let loose (6,4)
PICKET LINE — anagram (loose) of NICE KIP LET

25

Break the remainder (4)
REST — double def.

27

Once I'm in, it's kept for later (2,3)
ON ICE — ONCE with I inside

28

Rural mice run round like quicksilver (9)
MERCURIAL — anagram (run round) of RURAL MICE

29

Ship full of snake and toad masks left (8)
BOATLOAD — BOA (snake) and L (left) inside (masks) TOAD

30

Men agree, details are thin on the ground (6)
MEAGRE — MEn AGREe without last letters (de-tail)

Down

1

Had us try out during the week (8)
THURSDAY — anagram (out) of HAD US TRY

2

Christmas decoration is the first allowed into Moe (9)
MISTLETOE — IS T (first of the) LET (allowed) inside MOE

3

Jealous of English navy? Not a bit! (4)
ENVY — E (English), then NaVY without a

5

Sadly my edits were a hindrance (7)
STYMIED — anagram (sadly) of MY EDITS

6

Hello, what's your modum operandi? (3,2,3,2)
HOW DO YOU DO — cryptic def.

7

Jotted down the last few by heart (5)
WROTE — W (last letter of few) ROTE (by heart)

8

Bitches' doctrines? (6)
DOGMAS — cryptic def.

9

Uproar over forecourt's cost blow-out (6)
FURORE — anagram (over) of FoREcOURts without cost

14

Uncool lead-up but fair settlement (6,4)
SQUARE DEAL — SQUARE (uncool), anagram (up) of DEAL

17

Have a gander first before saying it's the spouting (9)
GUTTERING — G (first letter of gander) UTTERING (saying)

18

While it is wrong, sweetheart tells a harmless fib (5,3)
WHITE LIE — anagram (wrong) of WHILE IT, E (middle of sweet)

20

Resolve mid-meal quandary (7)
DILEMMA — anagram (resolve) of MID-MEAL

21

Some bogan attempt to build an overhead crane (6)
GANTRY — GAN (partial bogan) TRY (attempt)

22

Care less about comparable confidence and flair (6)
APLOMB — anagram (about) of cOMParABLe without care

24

Starts to check in on a mate (5)
CHINA — CH (first two letters of check) IN on A

26

Be furious when audience is a few men short (4)
FUME — homophone of FEW, MEn short