Some help with the following, please:
ACROSS:
1 Solitary criminal canned opium ( 11 )
Does "uncompanied" exist?
15 Knockout pair of rivers divided country(5)
????A
27 Drummer not so good: he's boring(7)
DOWN
6 I'm often pressed...(8)
D???B???
21 Look into sinfulness of deadly inventor(9)
Thanks for any help and rationale for the answers...