13a) This playwright lived with an artist (8)
?L?T?H?R gives, presumably, Fletcher - who lived with Beaumont. Why "artist", though?
And 18d has me stumped:
Dramatically a nephew (unknown) replacing son in Dickens? (7)
I have C?A?L?Y.
:(
Aha - but it ain't over till it's over: I am still ultimately stymied by 21d)
Very successful children's author's bargain book announced? (5)
I have S?E??, because I dunno whether 25a) is Bannatyne or Ballantyne.
Haven't enjoyed this one very much...