3971: Franglais by Nutmeg
For a Listener debut Nutmeg gave us a puzzle that was clearly explained in the preamble. “Half of the entries are words that are found in French as well as English. In clues to these, the definition is of the French word. To assist non-French speakers, one-word English definitions appear as extra words, one in each of the remaining clues.” As usual in crosswords (and in France) accents are ignored in upper case.

Extra words of English definitions are shown in square brackets.

1 Unstable Trucial State losing leader (joint) (12)
10 Start to build without acceptable base (4)
FOND FO(U)ND less U (acceptable)
11 Brainbox promoted in Council of Europe (5)
12 Endlessly stir round a second excellent [cordial] (6)
FAMOUS A MO in FUS(S) (cordial = 1d)
13 [Amorous] milk supplier finds uncle returning - tricky situation for Adelaide! (6)
MOOCOW COW (milk supplier) + OOM (reversed) (amorous = 10a)
14 A very [dark] black yarn (3)
ABB A + BB (very black) (dark = 26d)
16 Fashion covering nearly every part of body (5)|
17 Baron and prince combine arms (4)
18 Discover agent carrying deadly disease (4)
RAGE Hidden (la rage = rabies)
20 Holy boy's base (4)
PIED PI + ED(ward)
22 Indulge [supporters'] requests on radio (6)
PLEASE Homophone PLEAS (supporters = 17a)
24 Flash church backs grave (6)
ÉCLAIR CE (reversed) + LAIR (un éclair = a flash of lightening)
26 Doctors once let this hospital go, but not completely (4)
SANG SAN (hospital) + G(O) (sang = blood)
27 Study the canine, say (4)
DENT DEN (study) + T’ (the) (dent=tooth)
28 Bear [anger], graduate having left university (4)
BALU BA + L + U (university) (anger = 18a)
29 Mark several times [confessed] -- silver shilling stolen during service (5)
AGMAS AG (silver) + MASS less S (shilling) (confessed = 26a)
33 Bad mood among Labour's leaders (3)
MAL initial letters (mal=badly)
34 Pulled in both directions, Archer gets return ticket (6)
BILLET BI + TELL (reversed; ref. William Tell)
35 Losing heart, horse paces with sloth within shafts (6)
TRAITS  Shafts as in traits de lumière - shafts of light. TROTS less O containing AI (sloth)
36 Minor bovine [sickness]? (5)
LOWER 2 definitions (sickness = 33a)
37 Athletic half back representing Leeds, among others (4)
CITÉ (Athl)ETIC (reversed)
38 Builder sees Peter run off, grabbing Frenchman (12)
ENTREPRENEUR Anagram PETER RUN containing Rene
1 A y-yarn that's easy to get on with (7)
2 Vehicle on test reversed into metal [derrick] (6)
TOMBAC CAB + MOT (reversed) (derrick = 11a)
3 Popular working party to [select] ... (4, two words)
IN ON IN (popular) + ON (working party) (select = 19d)
4 ... purist put out about a more exalted ["name"] (7)
UPSTAIR Anagram PURIST + A (name = 37a)
5 Mail [delivery] disrupted in capital (4)
6 Short [hollow] column supporting advanced bridge system (4)
ACOL A (advanced) + COL(UMN) (hollow = 27a)
7 [Tycoon] shot up with nothing to hide, he swears? (7)
TROOPER REPORT (reversed) containing O (tycoon = 38a)
8 Where false teeth are [trouble] to deal with (11, three words)
ON ONE’S PLATE 2 definitions (trouble = 32 d)
9 Refurbished bare [accommodation], we're told (5)
NEWED Homophone NUDE (accommodation = 34a)
10 Productive enterprise from 1 cent invested in super allotment (11)
FABRICATION I + C (one cent) in FAB + RATION
15 Morag's wide [variegated] plait (5)
BRAID 2 definitions (variegated = 20a)
19 Cream cake's final ingredient not full of calories (5)
21 Horse gets fitter without [cake], he argues (7)
HAGGLER GG (horse) in HALER (cake = 24a)
22 PE turns nasty for [fake] humorist ... (7)
PUNSTER Anagram PE TURNS (fake = 10d)
23 ... MO rules out [unvarnished] apparatus (7)
EMULSOR Anagram MO RULES (unvarnished = 30d)
25 Enclosure with posts holds German with silk [stock] (6)
SAMITE MIT (with in German) in SAE (stock = 16a)
26 It piles up on shore as island's rising (5)
SABLE (Sand in French) ELBA’S reversed
30 Progenitrix used to be, but head flipped (4)
MÈRE WERE with W turned upside down
31 Leading [features] in theatre? (4)
ATOP AT OP(era) (features = 35a)
32 Memorable number fed by a staple food (4)
PAIN PIN containing A