“In DRIVER, a word is to be removed from each clue before solving. Letters formed by adding the initial letter of that word to the last letter of the clue answer define a word (A=1,27; B=2,28; etc). Solvers must reveal that word by highlighting seven of its examples, a total of 51 cells. Chambers Dictionary (2016) is recommended, but does not give 40ac (in OED) and 3dn (a fairly common term).”
The definition is TRUNKS OF TREES ARE MADE OF THIS HARD FIBROUS MATERIAL. After prolonged research, I am confident that I have the answer, the seven types of which are SAVANNA-WATTLE, SAPPAN, ALERCE, SANDAL, SAPELE, HICKORY, and MERANTI.
When one highlights those, the word WOOD appears in the grid, giving a very satisfying resolution.
Note that, in addition to the two answers mentioned in the preamble, 7 down does not appear in Chambers.
Notation
(xxx) = definition
[xxx] = (anagram/homophone/container/etc.) indicator
XXX* = anagram
< = reversal
warming = additional word
Please post a comment if the explanations are not clear.
| Across | |||
|---|---|---|---|
| T | 1 | CALLOW | Inexperienced CALLO |
| R | 5 | ACONITE | CON (Prisoner) N (number) I (one) [in] Malta ATE (swallowed) poison (7) |
| U | 11 | OPERON | Group O (of) PER (a) ON (forward) set of genes (6) |
| N | 12 | APAY | Old-fashioned orisons satisfy A (acting) P (priest)? AY (Yes)! (4) |
| K | 13 | GAME | Disabled field sport (4) |
| S | 16 | AVIAN | VIA (Road) [crossed by] A N (number) of exotic birds (5) |
| O | 17 | TELLURAL | URAL (River) [next to] colossal TELL (mound) of earth (8) |
| F | 18 | NOWT | Nothing like highland cattle (4) |
| T | 20 | TEA ROSE | Prickly shrub AROSE (came into view) [by] TE (THE [empty]) orchard (7, two words) |
| R | 21 | ENOW | < ONE (Joke) [about] W (women) old enough upstairs (4) |
| E | 22 | TERCETS | [Encryption of] {T ([primarily] TOP) SECRET}* lines of Latin verse (7) |
| E | 24 | TUTU | Source of poisonous berries [twice] < UT (as) juicy [from the east] (4) |
| S | 25 | PECKISH | Somewhat hungry PECK (jerk) [demolished] HIS* kipper (7) |
| A | 28 | TISANE | Herbal drink IS [consumed by] TANE (one Scottish} vegan (6) |
| R | 30 | CHICKEN | CHIC (Smart and fashionable) KEN (house of disrepute) frightened daughter (7) |
| E | 33 | SMEDDUM | SUM (Substance) [containing] MED (medium) D (density) fine rich powder (7) |
| M | 34 | BALDPATE | Wild duck D ([beginning to] DIVE) PAT (at the right time) [surrounded by] hostile BALE (group) (8) |
| A | 36 | TISRI | [Some] agenT IS rather RIsking a few weeks in the autumn (5) |
| D | 37 | UPHILL | Difficult PILL (ball) [stopped by] H (Henry) [after] U (United) regrouped (6) |
| E | 38 | RESAYS | Lecturer SAY (for example) [in] RES (residence) speaks again (6) |
| O | 39 | ELEPHANTINE | Ungainly joiner [repairing] {THE PLANE IN E (Spain)}* (11) |
| F | 40 | TREEBEAR | TREE (Box for one) nag BEAR (to carry) Georgia’s furry carnivore (8) |
| T | 41 | YALES | Y (Wye) ALE (antique festival)’S ample locks (5) |
| Down | |||
| H | 1 | CIGARETTE BUTT | [Awfully] {CUTE GREAT TIT B ([beginning to] BITE)}* the end of Napoleon’s snout (13, two words) |
| I | 2 | LUMINOUS | Very bright panama LUM (hat of Scotsman) – I (one) [with] NOUS (common sense) (8) |
| S | 3 | OPEN WOUND | OP (Operation) [on] EN (nurse) [with] WOUND (twisted) organ injury having exposed flesh (9, two words) |
| H | 4 | WELT | Natty blow dry (4) |
| A | 5 | ARIETTE | A little air IE (that’s) voiced [in] A RT (right) TE (note) (7) |
| R | 6 | COAL | COL (Pass) [over] A foreign char (4) |
| D | 7 | NAMUR | < RUMAN (Dusty European) [turned up] looting a Belgian battle site (5) |
| F | 8 | TAPAS | Mary snacks AP (before a meal) [in] TAS (Tasmania) (5) |
| I | 9 | EYELESS | Unable to see LESS (younger) pheasant [trailing] EYE (old brood) (7) |
| B | 10 | SAVANT | Accomplished horseman SAT (occupied a chair) [outside] VAN (mobile home) (6) |
| R | 14 | ALAR | A (Absolute) zealous LAR (god) with wings (4) |
| O | 15 | FROE | A tool just FOR* [shifting] E (earth) (4) |
| U | 19 | TAPED | Did record APE (copy) Queen [in] T (time) and D (depth)? (5) |
| S | 23 | THEORY | TORY (Right-winger) [concealing] HE (explosive) trading proposition (6) |
| M | 26 | KITTENY | Playful KITTY (Jack)[’s carrying] Noddy EN (EVEN [on vacation]) (7) |
| A | 27 | SKYSAIL | SAIL (Project) [involving] KY (Kentucky) S (son) – one superior to the royal official (7) |
| T | 29 | AEDILE | AE (Aged) DI (detective) [facing] LE (the old French) official from Rome (6) |
| E | 30 | CUTCHA | Makeshift CHA (tea) dance [introduced by] CUT (hack) (6) |
| R | 31 | CRISTA | < SIR (Knight) [up] [in] CT (court) A (accepted) cross questioning (6) |
| I | 32 | NOISES | Rumours no longer [worried] {SENIO |
| A | 33 | SAPOR | Flavour SAP (juice) [with] OR (yellow) ingredient (5) |
| L | 35 | PLEB | PLEA (Dispute) [with B (bachelor) for jeering A (active)] vulgarian (4) |
| C | A | L | L | O | W | A | C | O | N | I | T | E |
| I | S | U | O | P | E | R | O | N | A | P | A | Y |
| G | A | M | E | E | L | I | A | A | M | F | P | E |
| A | V | I | A | N | T | E | L | L | U | R | A | L |
| R | A | N | O | W | T | T | E | A | R | O | S | E |
| E | N | O | W | O | A | T | E | R | C | E | T | S |
| T | T | U | T | U | P | E | C | K | I | S | H | S |
| T | I | S | A | N | E | C | H | I | C | K | E | N |
| E | S | M | E | D | D | U | M | T | R | Y | O | O |
| B | A | L | D | P | A | T | E | T | I | S | R | I |
| U | P | H | I | L | L | C | R | E | S | A | Y | S |
| T | O | E | L | E | P | H | A | N | T | I | N | E |
| T | K | E | E | B | E | A | R | Y | A | L | E | S |
An enjoyable EV – in a long tradition of EV puzzles with letters shaped from thematic words. As I teased out the phrase made by the additions, it helped that in golf a DRIVER is also known as a WOOD.
Thanks to setter and blogger…