Dt 29,385

[nain05]

17dn Mean 50s lout shut away [8] ???????l
18dn shoot a troublemaker in European city [8] ???????A
24acc united supporters returned in chaos [5] ?????
27 acc Ambassador blocks Conservative plan [6] ??????
Many thanks for your help

[Lie-in King]

17d Closeted - 'close (mean; stingy) Ted (50s lout)'
18d Bud-a pest
24a Snafu - 'u(nited) fans' (back)
27a Theory - 'H(is/er) E(xcellency)' (in) 'Tory'