The unclued lights (all but one either hyphened or of two words) share a distinctive feature.

Across

1 Fun and games of conservative leader amongst those opposing him (6)
7 Cost out red herald’s tunic, once (6)
13 Less convincing Debussy composition …. (5, two words)
16 … and which gets first directed badly by this conductor (6, two words)
20 Belgrade’s football team swapped parts and took the lead (7)
21 Lowest form of bird life (6)
22 Rows between the wedding families! (6)
24 Cancels order for windscreens — not new (8)
26 Money invested in raffle, paid...