Times,25,897.

[red46]

15d, 2words,4.5. L??? ?????. Badly cooked cassoulet,one that can't be saved.
19a, 4lets, S???, Band's timeless collection.
21d, 6lets, ??????, Country's unknown capital doctors looking up.
22a, 8lets, ??????I?, What's afoot minutes before event in which second round's lost.
28a, 9lets, ??????d?e, Quickly get out unopened bid and become confused.

[jim360]

15d lost cause (anag. "cassoulet")

[Mamyalynne]

19 S(t)ash

21 Zambia - A1 BMA Z , all back

[Mamyalynne]

22 Moccasin - Mo + Occasi(o)n

[Lie-in King]

15d Lost cause - anag 'cassoulet'
19a S(T)ash
21d Zambia - 'z' (unknown, as in maths) + 'A1' (capital) & 'BMA' (doctors, all up)
22a Moccasin - 'm(inutes)' + 'occasi(o)n' (2nd "round" lost)
28a Skedaddle - '(a)sked' + 'addle'

[Mamyalynne]

28 Skedaddle - (A)Sked + Addle

[Mamyalynne]

^ Oi!

[Mamyalynne]

Sorry,ignore my parse for Moccasin totally wrong.

[Lie-in King]

Wot?

[red46]

Thanks, jim360, mamyalynne, lie-in king, for help.

[dannyk13]

15d.Lost cause (anagram of cassoulet)
19a.S(t)ash

[red46]

Thanks dannyk.