This is a cryptic crossword jigsaw fill: the clues are listed below, grouped by length (the only clues to have length in the standard parentheses are those having two words) and in alphabetical order in each group. When they are solved they can be arranged to fit in the grid in exactly one way.
Once the grid is filled, the numbered squares will spell out, in order, the expected (though fictional) feminine noun for a member of a famous group. Solvers should correct the spelling (change exactly one letter) to be the name of the group (this will produce real words in the grid, though arguably one of them is oxymoronic). Solvers should also highlight three surnames in the grid, of members of the group, and indicate which single letter should be changed elsewhere in the grid to find a fourth surname (sadly this change does not create real words).
Design a current for Malta
Tropical bird nests in Madagascan ironwood
Dye a duck
Half a square metre of paper is perfect! (1-3)
Schematic's second page missing a key...
...tone, for example, laid out
Last two thirds of push for small defense
No second impact to back of knee
Edmund's white with age and Henry's rather less masculine
My intention broadcast by Man, for example
Once illuminate starting letters in manuscript notes
Indian gardener -- bad one
Friar's opposite is mostly Capuchin
State occupied with Frozen Snowman
Dialect once supported by saint
No mate for milky white gemstone?
Local leftovers rot badly, son
After seconds of spiced cake, essay Stilton
High priest sets volcanic rock above man
American paid up for desired missing wife
A psi-sigma initial segment defines greatest orbital distance from centre
(Informal) Sound of car maker getting nothing
Demeter covers with wax...
...time after time, O Muse!
Lots of LA hormone takes Venetian to height of poetic inspiration
Stinking tide stirred up after most of reef is destroyed
Carry back: private secretary swallows quickly
Deflection into pocket -- Fagin offers a hiding place (2-3)
Calibrate without outliers -- sign of balance
US Saltpetre can reverse heading, right?
Celtic letters found in 'Van Gogh -- a memoir'
That woman, Vanessa, extremely indicates absence of vowel
Debauched beasts; most, worthless
Like thin plates tangling right animal
He examines and corrects reivers' discombobulation
Trace of life essential for glowing particle (5,5)
Parrot plague-host is iron-addled