Not only does she not believe gun ownership is a constitutional right, and refuse to answer the question twice, notice the professional parseltongue:

“if it is a constitutional right“… blah blah blah.

“Shall Not Be Infringed” seems pretty clear to most Americans, and is the basis for the Heller decision (Justice Antonin Scalia) Clinton refuses to name specifically; because to do so would prove her desire to eliminate the second amendment.
The Heller decision stemmed from the ridiculous Washington DC handgun bans.