match a single word character	/\w/
match a word	/\w+/
match a word at the start	/^\w+/
capture it	/^(\w+)/
bind the pattern to a string	$x =~ /^(\w+)/
assign captured word	my ( $word ) = $x =~ /^(\w+)/

The parentheses around $word are important.

Update: Reformatted