Allusions by MynoT

In this Christmas-themed puzzle, each of the twelve gifts in "The Twelve Days of Christmas" appeared in singular form (e.g. "Drummer", "Hen") in the grid and was to be highlighted. Wherever they appeared, the word itself was not clued but the wordplay led to the description or activity of the gift in the song, thus "Drumming", "Laying" etc. What made this difficult and a little unsatisfying for the solver was that the gifts themselves sometimes formed a full light, sometimes less, and sometimes overlapped more than one. Where the gift was less than a full light this left some part of the light with no wordplay at all (e.g. "Swansea" at 28D). Where it overlapped, there were lights clued with just a definition (e.g. "Ridge" at 46). None of this was unfair, but the differences in treatment meant that for this solver at least, the theme didn't feel very carefully worked out.

Finally, Gregson could make no sense of the reference in the preamble to "various correct orders". The thematic elements didn't seem to need any particular ordering.

Across
3 Foundation investing pounds in Swiss city (5)
BASLE (L inside BASE)
6 Apostle died for a joint (6)
SPAULD (S(aint) PAUL + D(ied))
11 Papal family's black secret rites (6)
BORGIA (B(lack) + ORGIA)
13 Energetic person's to see central sights of Motherwell... (4)
DOER (DO (see) + ER (middle letters of MOTHERWELL))
14 ...or go and get... (5)
BRING / GOLDEN (OR = Gold)
16 ...father on the way westwards for a drink in Ayr (4)
DRAP (PA + RD rev.)
18 Copywriter's put together a Dutch piece (5)
ADMAN (A + D(utch) + MAN)
19 Large space before a thousand (5)
ENORM (EN + OR (before) + M (thousand))
20 It's always on time beyond around Newcastle (5)
AYONT (AY (always) + ON + T(ime))
22 Kind of speed trap that doesn't start for about four weeks (4)
ADAR (RADAR minus first letter)
24 Making a bid for something trifling (8)
BIRDSEED / CALLING (Two meanings)
26 Visible old dwelling near Suffolk town (5, two words)
IN EYE (IN (old dwelling place) + EYE (town))
27 Is hot head following with snake's virulence? (11)
WASPISHNESS (W(ith) + ASP + IS + H(ot) + NESS)
29 Note the Northern women accepted ultimate sanctions (5)
FATWA (FA (note) + T' (the) + W(omen) + A(ccepted))
30 Graft to get European money or old Russian coin (8)
IMPERIAL (IMP + E(uropean) + RIAL)
32 Stuff waste back (4)
CRAM (MARC rev.)
33 Vermouth's out! (5)
HENCE / FRENCH (Two meanings)
36 Overwhelm with amazement with old English as common language (5)
KOINE (K.O. + IN + E(nglish))
38 Legal auditions certainly must be about right? (5)
OYERS (R inside O YES)
41 Drawing device is the way of the warrior (4)
BUDO / TURTLE (Two meanings)
42 Festival (5)
VESAK (Definition)
43 Jersey, possibly paisley, affording no benefit outside (4)
ISLE (Inside PAY, forms PAISLEY)
44 A bit of nationalism in German spirit is nothing at the Boers (6)
NIXNIE (N (first letter of NATIONALISM) inside NIXIE)
45 Leave tuna, perhaps (6)
DEPART / PEAR TREE (Two meanings)
46 As (5)
RIDGE (Definition)

Down
1 Garment for man of cloth in Egypt (4)
ABBA (Two meanings)
2 Measure quiet meadow producing expression of surprise (5)
LORDY / LEAPING (LEA (measure) + P (quiet) + ING (meadow))
"Meadow" usually leads to LEA so this was a very confusing clue.
3 Completely fill ship with money for government (4)
BRIM (BRIG with M (money) replacing G(overnment))
4 Archer, for one, is cross (4)
SIGN (Two meanings)
5 One stone's left out in putting away measure of slate (4)
LADY / DANCING (DISTANCING minus I + ST(one))
6 One in third year is sober about wages (6)
SPAYAD (PAY inside SAD)
7 Very hot peppery substance (8)
PIPERINE / PIPING (Two meanings)
8 Port in Spain, one of four bases (7)
ADENINE (ADEN + IN + E (Spain))
9 Scaly substance returning among carpellates (5)
LEPRA (Hidden rev. in cARPELlates)
10 House deserted by strange old couple (4)
DRUM / DRUMMING (D(eserted) + RUM + MING)
12 Manipulating attendants at wedding (11)
BRIDESMAIDS / MILKING (Two meanings)
15 Grand mother's bread (3)
NAN (Two meanings)
17 Enters money held in notes? On the contrary (7, two words)
COMES IN (MES (notes) inside COIN)
20 Sailor's approximately 30 cm behind (5)
ABAFT (AB + A + FT (foot))
21 "Deceptions for the audience follow", mouths Portia,for example (7)
ORATRIX (ORA (mouths) + homophone TRICKS)
23 Dog (5)
MERLE (Definition)
25 Key room at court (8, two words)
SPACE BAR (SPACE + BAR)
28 Feeling dizzy in Welsh city (7)
SWANSEA / SWIMMING (Two meanings)
30 Break into posh car and drive against the stream in it (6)
IRRUPT (RR (Rolls-Royce) + UP inside IT)
31 Get a supply of good iron (5)
GOOSE / LAYING (LAY IN + G(ood))
34 Family in house lacking theological learning (3)
EYE (EYRIE minus RI)
35 Scots neck witch without success (that's accidental) (5)
CRAIG (CRAIGFLUKE minus FLUKE)
A good thing CRAIGFLUKE was adjacent to CRAIG in Chambers, else this wordplay might have remained forever a mystery.
36 Chief to serve fish (4)
KAID (KA + ID)
37 Corporal structures company going to Northern Ireland (4)
CONI (CO(mpany) + NI)
38 Old poet upset at start of marital break-up (4)
OVID (Reversed at start of DIVOrce)
39 Menial personnel intermittently employed (4)
ESNE (Alternate letters of PERSONNEL)
40 Asymmetrical coping-stone (4)
SKEW (Two meanings)