Da Grab an’ Bash: When you make
attacks for a Brute Boss armed with a Boss
Klaw and Brute Smasha, roll to hit with
the Boss Klaw first. If it scores any hits,
then a model from the target unit has been
grabbed by the Klaw, and the Brute Smasha
hits automatically as long as it is used to
attack the same target unit.
I've recently been thinking about this and to me it sounds like
RAW on the warscroll the term
hit/hits is defined as "passes a successful hit check", not deals a wound (even though that sounds logical also).
Which is still really good, as you would only then have to pass the to wound checks for the Smasha. Anyways, that's how I play it.