Sorry it's me again, I'm still stuck, these are the last ones I promise.
3ac Chap from a mega city.... 5L - M - A -.
13ac Mass - it's far from over. 3L T - N.
27ac Seers are back, of course. 4L - - - S
2dn 2It's a city," Mark states 5L M - L - O
20dn Why gin upset a company. 5L P - R - -.
Thanks scorpiojo. I still don't really see why we use the Y from whY. I know answers are sometimes hidden in the clue but in this case it's running backwards after gin is replaced by trap.