Novel way to prepare extending the patio? (3,3,4,5)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

If you don’t know the Evelyn Waugh novel, this could be fairly opaque, but it’s represented by a succinct suggestion in the rest of the clue for how to extend a paved area such as a patio. You could try taking up the TLS, where this sort of entry crops up regularly.