Hey again Susan,
You’re over thinking it I think. LOS ANGELES is just an example of a metropolis – ie, a big city.
Thank you.
Answers to these last two remaining clues not being requested here! However, if GIN PALACES is wrong, could you please say, and if Kelvin has anything to do with absolute zero, a yes or no would be appreciated.
Trap positions American inside pretentious public house (3,7)
G - - - A – A – E –
I’m fairly sure GINPALACES correct?
Which leaves just one:
Devil getting on with mostly agreeable Kelvin (3,4) – L - - - - -
Sixth letter could be C or R.
And of course the answer is oLD NICK.
Well, that's the record time so far for the cryptic's completion.

I shall try one or two of the mid-week cryptics, but then of course, the answers are available the next day.
Mind you, I'm still not sure where Kelvin comes in.