I just figured out how to do this:
$ zhelp() { man zshbuiltins | less -p "^ $1" }
$ zhelp read
read [ -rszpqAclneE ] [ -t [ num ] ] [ -k [
num ] ] [ -d delim ]
[ -u n ] [ name[?prompt] ] [ name ... ]
....
... simple and effective, but I'll bet someone has something
better.