Thanks Falcon for this morning’s challenge.
Nothing too tricky here. I enjoyed this. Good mix of clue types. Great anagram in 14a, and 17a deserves a special mention!

Across
1 Heading off to give credit to journalist (6)
SCRIBE
[a]SCRIBE (to give credit to, heading off)
4 To that extent, illegally copy what Higgins taught Doolittle to do? (8)
ASPIRATE
AS (to that extent) PIRATE (illegally copy)
(Reference to “Pygmalion” characters)
9 Concern shown after conclusion of government paper (6)
TISSUE
ISSUE (concern) shown after [governmen]T (conclusion of)
10 Knives and forks etc for an American’s apartment are needed by wife (8)
FLATWARE
FLAT (apartment) + ARE + W (wife)
12 Below par, not in usual shape? (3,2,4)
OUT OF FORM
Double definition
13 Actor Claude, as painter in beginning of Séraphine (5)
RAINS
RA (painter) + IN + [S]eraphine (beginning of)
14 Shetland leader lost in strait (3,11)
THE DARDANELLES
(SHETLAND LEADER)* (*lost)
17 Satisfying stop in place that sells juice (7,7)
FILLING STATION
FILLING (satisfying) STATION (stop)
21 Cassette sent over intercepted by unknown emigrant (5)
EXPAT
(TAPE)< (cassette, <sent over) intercepted by X (unknown)
22 Develop complex (9)
ELABORATE
Double definition
24 Not quite done during a dance, most importantly (5,3)
ABOVE ALL
OVE[r] (done, not quite) during A BALL (a dance)
25 Allowed to adopt mischievous child, one not easily got rid of! (6)
LIMPET
LET (allowed) to adopt IMP (mischievous child)
26 Paper in stand I look at briefly (8)
TREATISE
TREAT (stand) + I SE[e] (I look at, briefly)
27 Church worker from Essex, tongue-tied (6)
SEXTON
[es]SEX TON[gue-tied] (from)
Down
1 Leave, determined to go on Scottish river (3,5)
SET FORTH
SET (determined) to go on FORTH (Scottish river)
2 Prize dog not right after run out (7)
ROSETTE
SETTE[r] (dog, not right) + R O (run out)
3 Outspoken, expert about lake (5)
BLUFF
BUFF (expert) about L (lake)
5 Lone battle to secure plant (8,4)
SOLOMONS SEAL
SOLO (lone) + MONS (battle) + SEAL (to secure)
6 Among other things changed at airline (5,4)
INTER ALIA
(AT AIRLINE)* (*changed)
7 A sin involving a king’s greed (7)
AVARICE
A VICE (a sin) involving A R (a king)
8 Very moving verse, start of “Ozymandias” (4,2)
EVER SO
(VERSE)* (*moving) + [O]zymandias] (start of)
11 Welcome payments in precious metal? He will in different ones (6,6)
GOLDEN HELLOS
GOLD (precious metal) + HE’LL (he will) on (ONES)* (*different)
15 Completely over-the-top about pieces in plot (9)
ALLOTMENT
ALL (completely) + OTT (over-the-top) about MEN (pieces)
16 Left bishop inside, yet to lose (8)
UNBEATEN
UNEATEN (left) + B (bishop, inside)
18 Scamp learning to beg (7)
IMPLORE
IMP (scamp) + LORE (learning)
19 Up against it travelling to Spain (2,1,4)
IN A SPOT
(TO SPAIN)* (travelling)
20 Leave region after editor turned up (6)
DEPART
PART (region) after (ED)< (editor, <turned up)
23 Old fine suspended (2,3)
ON ICE
O (old) + NICE (fine)
A bit of a toughie from Falcon today, I thought — for instance, I’m ancient but have never come across 10ac FLATWARE before. I agree with Teacow’s special mentions — plus I enjoyed 5dn SOLOMON’S SEAL. Thanks to both.
Nice crossword. 11dn is a new term for me but easy to parse from the clarity of the clue. Thanks Falcon and Teacow.
Thanks to Falcon and Teacow. I did not know SOLOMONS SEAL or GOLDEN HELLOS, but I agree about the clarity of the clues. I needed all the crossers to get ROSETTE, my LOI.
Thanks Falcon and Teacow
Felt like Falcon and turned the difficulty ratchet up a notch or two in this one, I think mainly for a couple of newish terms and the secondary or tertiary definitions of some words. FLATWARE, SOLOMON’S SEAL and the actor RAINS were all new terms for me.
Did like both of the clues mentioned in the blog.
Finished in the SW corner with FILLING STATION (unusual term for a servo), ALLOTMENT and TREATISE the last few in.