ACROSS

 1  and 6 Make a formal speech to the dancers, as one might do before driving off. (7,3,4)

 10  It’s crazy, fame! Fur makes this winter warmer. (7)

11  At the end of labor, the CIA improperly has a large number making a kind of acid. (7)

12  The Bayeux example is noted, but you get certain recordings with effort. (8)

13  The quest for one is legendary, with a large number going by what the train runs on. (5)

15  A broken-down stair gets you moving! (5)

17  Turns out to be around what many a business tacks on its name, but they’re found away from big cities. (9)

19  A small cafe in Paris makes the state troubled about what belongs to me. (9)

21  ”Sir,” for example–submit it legally for show. (5)

23  What? Not a loss once more! (5)

24  You’ll have to praise a number, to start with, to find another number–from poppies! (8)

27  Almost all play has a club, for example–
and this might advertise it. (7)

28 , 1 down and 26 down Diamond enthusiasts might want to have them. (Cotton or wool to confirm with confidence how old you are!) (7,8)

29  Newt might be an example of such, and get left so they can display it. (4)

30  Makes up the material on a sort of seat. (10)

DOWN

 1  See 28 across

 2  Put his feet down and up around the guy not working now. (7)

 3  What’s the point to a crazy duel when you get to escape by trickery? (5)

 4  Not out, and not finishing typing what might relate to a holding force on the baby’s necessity? (6-3)

 5  Just a favorite part-time activity, but gets a little shot in the barge. (5)

 7  Possibly coy maneuver of the CIA, which proves out of date. (7)

 8  Black doesn’t start to desire the queen, due to a ho-hum appearance. (10)

 9  Hauled in bad parlance the essential part for one who might dish out a dose. (8)

14  Commanded the unknown symbol to end up plentiful! (You shouldn’t set one for the kids!) (3,7)

16  One from Italy accompanies a Scotsman to present one from Bucharest. (8)

18  It’s not “in,” and more insensitive, to have more fighters on your side! (9)

20  Likely found at elevenses, or at 4 pm, but teacher loses her art to prove it! (3-4)

22  Traveler–stout, disheveled–moves around the little, very little state. (7)

24  The tattooed lady is disturbed daily. (5)

25  City in Italy rises where there’s room at the top. (5)

26  See 28 across