It's clearer in context:

Oh where is young Frankie and how he could ride
And Johnnie the light-hearted boy?
They tell me that lately he's taken a bride
A benedict's life to enjoy.

I believe this term comes from Shakespeare's 'Much Ado about Nothing,' in which Beatrice and Benedick are first at each other's throats, then are finagled into falling in love. There's a will-known line something like, "Here comes Benedick, the married man."