" Thanks for the advice. It is indeed Acer palmatum. The leaf scorch
actually
occurred last summer and resulted in a bit of dieback at the tips as well.
It has recovered well this year but there are one or two dead branches and
the tree as a whole has a rather unattractive shape (unusual in A.
palmatum). I was really just thinking along the lines of a light prune to
encourage bushy growth, not a wholesale hack back!

I should also say that the tree is still quite young (about 3' high)

I bought my Acer palmatum very cheap, about this time of year, because it
was looking very sorry for itself. I gave it a light pruning and it looked
great the following year.

I'd say, go with instinct. Only prune out what is absolutely necessary to
make an attractive shape.

Natalie