6D. Without doubt, Charlie got better opener out (7) A---R-D think it is assured but not sure why.
10A. Benny and Oscar in dash? Only part of it (6) --E-D- think it is speedo but not sure why.
21A. Express poll, support unchanged (2,2) -S,-S think it is as,is again not sure why
Many thanks in advance
21a. I think "poll" can mean HEAD or TOP. Support (for an idea) is BASIS. So, if you take off ( EXPRESS) the top of BASIS you get
AS IS. Rather obscure and convoluted!