Having the keyword in title is a "must" if you are really serious about competing for a keyword term.
By itself, It doesn't guarantee first page rankings. Keyword in the title tells the search engines right off the bat what your website is about.
If you don't have it, you would have to create a good number of backlinks with proper anchor-text to have the same effect (to be placed in the right search results).
Sorry you don't understand what i would say
some website have only one word in title and this word is the keyword
is good for seo put only one word in title?