I hope it's all right to do this a bit early. I'm going to be briefer than usual because I just have my phone at hand, and large fingers. I especially appreciated the topical clues, about the LA quakes, Brexit, and the British ambassador (e.g., stevea @2, ginge @18 [lovely structure]), but of course enjoyed reading all of them. I'm going with kt's concise entry @12:
Singular, lacking gravity, phoney, aloof (7)
Your prize:
https://m.youtube.com/watch?v=uZtsBQWHrHo
(I don't understand why anyone would try to "improve" the profound beauty of our island, whence I'm posting, with a Japanese garden.)
Thanks ever so much, faithful setters.