2406: Heptad

Clockwise round the grid from 6 run the names (9,5,7,6,8,7,8) of the leading members of a group. The unchecked and corner letters could make SILVER INVENTORS RUN AROUND and 18 is an anagram of the group’s name (two words). An English version of the name (two words) the group gave to a seminal work will appear diagonally in the completed grid and must be shaded. Ignore one accent.
 

Across

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Yascha Mounk

Europe must be stronger, or it will die

9    Stunner somersaults with worried screech (7)
10    Work encapsulating dry painter’s charm (7)
11    Dancing display (skipping tango, of course) (4)
13    Letter to the Hebrews in honour of religion (6)
15    Enzyme with round shape? No chance! (5)
17    Pop’s shrinking (3)
19    Lovely soul secure in fantasy world (9)
20    Snake studied in extended state (7)
22    Busy hôtel-Dieu finally excised organ (8, two words)
23    Twerp is backing protest (5, hyphened)
24    Sister reserves afternoon time for old relative (5)
26    Tissue wrapping polled poison plant (8)
29    Is cutting wind special around Nutmeg State? (7)
32    Bad children catching ball in galleries (9)
34    Expert swimmer, reverse of unskilful (3)
36    Enthusiasm of top musician mummy shunned (5)
37    Bats hate neon gas (6)
38    Place a great many talked about (4)
39    Restaurant contains tree with climbing plant (trimmed) (7)
40    Hostellers rallied without her in town halls (7)
 

Down

1    Child quite upset coming to steppes (6)
2    No Scots sharing trumpet of silver (5)
3    Part of plant people note (6)
4    Co-diners demanding dog’s dinner (4)
5    Shirt with panache, old president brought over (7)
7    Musketeer hosts most excellent functions (7, hyphened)
8    Licentiate with gold carriage (6)
12    Spanish lady kept secret seaweed (7)
14    Russian lass houses a thousand dwellers in boats (6)
16    Poet’s love-song is bright, involving alto and tenor (8)
18    Very fair lady, oddly brainless, runs away (8)
21    MCPs live in central Russia...