When voting to delete an answer in the review queue there is an option
link only (and not spam)
However, there is no such option when actually flagging answers. When flagging link-only answers I usually use either
not an answer
This was posted as an answer, but it does not attempt to answer the question. It should possibly be an edit, a comment, another question, or deleted altogether.
or
in need of moderator intervention
so I can add an explanation. I usually just put something like "Link only." Both of these have been picked up and resulted in the answer being deleted. But for the sake of consistency, what should I really tag such answers?