Bare Bones

[turnipface]

4a spread grease eliminating a second departure 6 letters
5d youngster left keys first 3 letters
7d decline is accidental before Autumn 2 words Short Fall ???
12a calm about award going round Placate ???

[mallyh]

4a egress
5d gal
7d short fall
12a placate

[MargoTester]

Egress
Gal
Shortfall
Placate

[Lie-in King]

4a Egress - anag 'gre(a)se' (no 'a') + 's(econd)'
5d Gal - 'G A' (notes) + 'l(eft)'
7d Sharp fall (accidental; sharp; music)
12a Yes - 'plate' (award, round) 'c(irc)a' (about)

[turnipface]

Thank you all