The unclued lights (including a pair, one word of which has to be read in reverse) are each somehow related to one other. Two grid entries are of two words and one (jocular) entry has four words and includes an apostrophe.

Across

10            Where lines meet new lines (4)

12            Payment to landlord as the Earth moved? (6,4)

14            Regular replay for City (3)

17            Awfully eager to acquiesce (5)

18            Aussie fish for swell at 40 (3,4)

19            Former EU President, 27, sadly lost sou (6)

22            The lad’s steed regularly expressed disapproval (6)

24            It’s criminal that the clergyman’s lost his head (5)

27            Not to be sniffed...