Sunday Post Cryptic

[Mags22]

12a - alien seen in bar,selling on high street ?e???l retail ? also stuck on 13d.A detective sergeant among twelve etc. ??m ?u ?n - have put shout out for 20a. hich may be wrong and putting letters wrong. Grateful for any help

[roslyn251254]

12a yes - ET is the alien inside rail(bar)

[frugalfred]

12. yes retail - alien is ET, remember the film? Bar - rail

[bibblebub]

12a) yes - ET inside 'rail'

13d) a = A, detective sergeant = DS, twelve = NOON
-> a nDSoon (and so on)

[frugalfred]

13d seen as "and so on"

[kettledrum]

13d and so on
20a shoot out