18a) 10 briefly banned from smoking freely in capital(5) M?N??
19d) Quiz champion on walk flummoxed by student (4-3) ???? ??L
23d) Comedian's art? It upset China (6)
27a) Harry is last to collect euros and depart (3,4) ??T ????L
28a) It's fabulous finding nickel and cobalt in vessel (7) ????O??
All help much appreciated