Much orchestral music has A as well as Bb parts. It is possible to play the A parts on Bb but, with the 1/2 tone change, that can land you in very awkward keys. The written range is the same on both instruments.
Re: Clarinet in A key? 15:14 on Thursday, May 18, 2017
daphnis and chloe was written for A clarinet, but we ended up transposing it back to b flat to make the riffs a bit easier...either way it was very difficult....check it out.