White should simply retreat from to
, not allowing Black to play a in sente. When
crawls further,
can block because this is a tiger's mouth. So Black dies as explained in the L-group page.
If white plays , then
threatens to make a living shape (see the L-group page for details). If white tries to kill with
, then black connects to the outside with
. Alternatively, white could try
at
, but then black lives by playing
at a.