The unclued Across lights are of a kind when preceded by one word, as are the unclued Down lights (one pair) when preceded by another. Brewer confirms them all.

Across

1 Pointless dissertations are more than this (5)

4 Breathing disorder altered my shape – and me! (9)

9 Companion dressed in fragrant black and white (10)

11 With openers of exceptional note, Surrey usually enforce follow on (5)

12 Time passed quickly, say – it’s sickening (7, two words)

14 Spare change – in Turkey, once? (5)

15 Exult as colonel finally spikes attack (5)

21 Quiet...